Hybrid binary catalysts, methods and uses thereof

ABSTRACT

The present disclosure describes hybrid binary catalysts (HBCs) that can be used as engine aftertreatment catalyst compositions. The HBCs provide solutions to the challenges facing emissions control. In general, the HBCs include a porous primary catalyst and a secondary catalyst. The secondary catalyst partial coats the surfaces (e.g., the internal porous surface and/or the external surface) of the primary catalyst resulting in a hybridized composition. The synthesis of the HBCs can provide a primary catalyst whose entire surface, or portions thereof, can be coated with the secondary catalyst.

BACKGROUND

Internal combustion engine exhaust emissions, and especially dieselengine exhaust emissions, have recently come under scrutiny with theadvent of stricter regulations, both in the U.S. and abroad. Whilediesel engines are known to be more economical to run than spark-ignitedengines, diesel engines inherently suffer disadvantages in the area ofemissions. For example, in a diesel engine, fuel is injected during thecompression stroke, as opposed to during the intake stroke in aspark-ignited engine. As a result, a diesel engine has less time tothoroughly mix the air and fuel before ignition occurs. The consequenceis that diesel engine exhaust contains incompletely burned fuel known asparticulate matter, or “soot”. In addition to particulate matter,internal combustion engines including diesel engines produce a number ofcombustion products including hydrocarbons (“HC”), carbon monoxide(“CO”), nitrogen oxides (“NO_(x)”), and sulfur oxides (“SO_(x)”).Aftertreatment systems may be utilized to reduce or eliminate emissionsof these and other combustion products.

FIG. 1A shows a block diagram providing a brief overview of a vehiclepowertrain. The components include an internal combustion engine 20 inflow communication with one or more selected components of an exhaustaftertreatment system 24. The exhaust aftertreatment system 24optionally includes a catalyst system 96 upstream of a particulatefilter 100. In the embodiment shown, the catalyst system 96 is a dieseloxidation catalyst (DOC) 96 coupled in flow communication to receive andtreat exhaust from the engine 20. The DOC 96 is preferably aflow-through device that includes either a honeycomb-like or plate-likesubstrate. The substrate has a surface area that includes (e.g., iscoated with) a catalyst. The catalyst can be an oxidation catalyst,which can include a precious metal catalyst, such as platinum orpalladium, for rapid conversion of hydrocarbons, carbon monoxide, andnitric oxides in the engine exhaust gas into carbon dioxide, nitrogen,water, or NO₂.

Once the exhaust has flowed through DOC 96, the diesel particulatefilter (DPF) 100 is utilized to capture unwanted diesel particulatematter from the flow of exhaust gas exiting engine 20, by flowingexhaust across the walls of DPF channels. The diesel particulate matterincludes sub-micron sized solid and liquid particles found in dieselexhaust. The DPF 100 can be manufactured from a variety of materialsincluding but not limited to cordierite, silicon carbide, and/or otherhigh temperature oxide ceramics.

The treated exhaust gases can then proceed through a compartmentcontaining a diesel exhaust fluid (DEF) doser 102 for the introductionof a reductant, such as ammonia or a urea solution. The exhaust gasesthen flow to a selective catalytic reduction (SCR) system 104, which caninclude a catalytic core having a selective catalytic reduction catalyst(SCR catalyst) loaded thereon.

System 24 can include one or more sensors (not illustrated) associatedwith components of the system 24, such as one or more temperaturesensors, NO_(x) sensor, NH₃ sensor, oxygen sensor, mass flow sensor,particulate sensor, and a pressure sensor.

As discussed above, the exhaust aftertreatment system 24 includes aSelective Catalytic Reduction (SCR) system 104. The SCR system 104includes a selective catalytic reduction catalyst which interacts withNO_(x) gases to convert the NO_(x) gases into N₂ and water, in thepresence of an ammonia reductant. The overall reactions of NO_(x)reductions in SCR are shown below.

4NO+4NH₃+O₂→4N₂+6H₂O  (1)

6NO₂+8NH₃→7N₂+12H₂O  (2)

2NH₃+NO+NO₂→2N₂+3H₂O  (3)

Where Equation (1) represents a standard SCR reaction and Equation (3)represents a fast SCR reaction.

The performance of the SCR catalyst is often counterbalanced by catalystdurability. This challenge is further compounded by the increasinglystringent emissions regulatory demands on the one hand, and the economicpressure surrounding fuel economy on the other. Furthermore, theperformance of the SCR catalyst is influenced by the level of engine outNO_(x) (EO NO_(x)) that has to be processed by the SCR catalyst. Thecurrent trend is in the direction of higher engine out NO_(x) to improvefuel economy, while emission levels are simultaneously being reduced.For example, at present, EO NO_(x) can reach as high as 7 g/kW-hr for atleast a short period of time. However, it is anticipated that in thefuture, there will be a move towards very low tailpipe NO_(x) (e.g.,decreasing from about 0.2 to about 0.02 g/kW-hr).

High EO NO_(x) has been shown to result in urea deposit build up in theSCR, due to the extremely high levels of diesel exhaust fluid that isintroduced into the system, and insufficient residence time for completedecomposition to form NH₃. The formation and accumulation of ureadeposits on the SCR catalyst can result in severe damage to both thechemical and physical integrity of the SCR coating. Furthermore, thehigh intensity of diesel exhaust fluid dosing and the relatively longduration of the dosing in urea decomposition reactor 102 can result inlarge quantities of water being released onto the SCR catalyst. As theSCR catalyst can be primarily composed of zeolites, which are powerfulwater adsorbing materials, the quantities of water can present a problemwith both durability and cold start performance of the SCR catalyst.

At low EO NO_(x) conditions, challenges are similar to those presentunder extended idling and cold start conditions. In other words, whenSCR temperatures are too low for diesel exhaust fluid dosing and normalSCR operation (between about 250-450° C.), other strategies are requiredto meet emissions standards.

Without wishing to be bound by theory, it is believed that the advent ofengine gas recirculation (EGR) has resulted in reduced peak in-cylindertemperatures for combustion to reduce engine out NO_(x). The reducedpeak in-cylinder temperatures are highly desirable from an emissionscontrol perspective. However, the lower peak in-cylinder temperaturesalso result in undesirable lower fuel economy. The reduced engineexhaust temperatures that result from increasing use of EGR also have anegative impact on cold-start conditions for engine aftertreatmentsystem (EAS) performance. Effective emissions control by EAS requirestemperatures of at least 200° C. to be attained before DEF dosing maycommence. Therefore, during the EAS heat-up period under cold-startconditions (i.e., at temperatures of less than 200° C.), there is noemissions control.

Some challenges that are encountered in emissions control include:

(1) Cold-start conditions with relatively low engine exhausttemperatures can be addressed by close coupling the SCR to the engine toachieve maximum heat-up rate, with exposure of the SCR catalyst tonon-pretreated exhaust directly from the engine. However, only partialNO_(x) reduction can be achieved in this manner. Therefore, a seconddownstream SCR (or a SCRF) will be required.

(2) Increased system size and complexity arise when the EAS includes aclose coupled zeolite-based SCR, therefore, a DOC upstream of the SCR isrequired for NO₂-make for optimal performance, with a DEF doser and anammonia slip catalyst (ASC), also called an ammonia oxidation catalyst(AMOX), downstream of the SCR to decrease NH₃ slip into the DOC. In someembodiments, while a close coupled vanadia-based SCR would not require aDOC upstream of the SCR, there exists a risk of sublimed vanadiumescaping into the environment.

(3) Space limitations for close coupling requires that the EAS be mademore compact, for example, by combining SCR and DPF to form a SCRF,which presents the following challenges:

-   -   (i) Competition between the fast SCR reaction and soot oxidation        reaction for the available NO₂ from the DOC;    -   (ii) No passive soot oxidation, because platinum group metals        (PGMs) cannot be used on the DPF substrate due to the presence        of NH₃ for the SCR reaction. Oxidation of NH₃ with PGMs also        produces N₂O, which is an undesirable greenhouse gas.    -   (iii) Finally, the reduced ash loading capacity of the SCRF        relative to a DPF and the associated higher pressure change (AP)        dictate a shorter ash cleaning interval and cost of ownership        for the customer.

(4) The potential for increased poisoning and hydrothermal aging of EAScatalysts are a major concern that arises from both close coupling ofthe SCR and in particular, when SCR on DPF (i.e., SCRF) technologies areemployed.

(5) Increasingly stringent emissions regulations are expected to beenforced by the year 2021; including tailpipe (TP) NO_(x)≤0.02 g/kw-hr,lower N₂O emissions standards, and generally tightened greenhouse gasregulation.

Thus, there is a need for engine aftertreatment catalysts that canaddress the challenges facing emission control. The present disclosureseeks to fulfill these needs and provides further related advantages.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

In one aspect, the disclosure features an engine aftertreatment catalystcomposition, including a plurality of metal oxide nanoparticleshybridized to a metal zeolite, wherein the metal oxide nanoparticle hasa maximum dimension of from 0.1 to 50 nm.

In another aspect, the disclosure features a method of making an engineaftertreatment catalyst composition, including providing an aqueoussolution including a chelating agent and a metal oxide precursorselected from ZrOCl₂.8H₂O, NaVO₃, BaCl₂, (NH₄)₆Ce⁴⁺(NO₃)₄, KMnO₄,Co(NO₃)₂, Cr(NO₃)₃, CaCl₂, barium nitrate, ortho phosphoric acid,ammonium molybdate tetrahydrate, calcium nitrate tetrahydrate, nickelnitrate, titanium chloride, and tungsten chloride; mixing the aqueoussolution comprising the chelating agent and the metal oxide precursorwith a metal zeolite to provide a metal oxide precursor-coated metalzeolite, and calcining the metal oxide precursor-coated metal zeolite toprovide the engine aftertreatment catalyst composition, wherein theengine after treatment catalyst composition includes a plurality ofmetal oxide nanoparticles bound to the metal zeolite.

In yet another aspect, the disclosure features a method of reducingNO_(x) in diesel engine exhaust in a selective catalytic reductionsystem, including exposing a NO_(x-)containing diesel engine exhaust toa catalyst composition described above, wherein the catalyst compositionis disposed on or within a catalyst support structure.

Embodiments can include one or more of the following features.

The metal oxide in the engine aftertreatment catalyst compositiondescribed above can be hybridized to atoms located on a portion of anexterior surface of the metal zeolite. In any of the above-describedembodiments, the metal oxide nanoparticle can have a maximum dimensionof from 0.1 to 30 nm (e.g., from 0.1 to 10 nm, or from 0.1 to 5 nm); theengine aftertreatment catalyst composition can have from 0.5 wt % to 50wt % (e.g., from 0.5 wt % to 30 wt %) of a plurality of metal oxidenanoparticles; the metal oxide nanoparticle can be selected from ceriumoxide, titanium oxide, zirconium oxide, aluminum oxide, silicon oxide,hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromiumoxide, molybdenum oxide, tungsten oxide, ruthenium oxide, rhodium oxide,iridium oxide, nickel oxide, barium oxide, yttrium oxide, scandiumoxide, calcium oxide, barium oxide, manganese oxide, lanthanum oxide,strontium oxide, cobalt oxide, and any combination thereof; and/or themetal oxide nanoparticle is selected from the group consisting ofzirconium oxide, vanadium oxide, cerium oxide, manganese oxide, chromiumoxide, cobalt oxide, titanium oxide, tungsten oxide, barium oxide, andany combination thereof.

In any of the above-described engine aftertreatment catalystcompositions, the metal oxide nanoparticle can further include acationic dopant; the cationic dopant can be an oxide including Mg²⁺,Cu²⁺Cu+, Ni²⁺, Ti⁴⁺, V⁴⁺, Nb⁴⁺, Ta⁵⁺, Cr³⁺, Zr⁴⁺, Mo³⁺, W⁶⁺, W³⁺, Mn²⁺,Fe³⁺, Zn²⁺, Ga³⁺, Al³⁺, In³⁺, Ge⁴⁺, Si⁴⁺, Co²⁺, Ni²⁺, Ba²⁺, La³⁺, Ce⁴⁺,Nb⁵⁺, Sr²⁺, Pt²⁺, Pd²⁺, Rh²⁺, and any combination thereof; and/or thecationic dopant can be an oxide including Pt²⁺, Pd²⁺, and Rh²⁺.

In any of the above-described engine aftertreatment catalystcompositions, the metal oxide nanoparticle can be selected fromCeO₂:ZrO₂, Y₂O₃:CeO₂, BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃,Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of O that counterbalances Zrand Ca cations of the metal oxide, Zr_(0.5)Ba_(0.5)Mn₃O₄,Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of O that counterbalances Baand Zr cations of the metal oxide, Zr_(0.5)Ba_(0.5)CrO₃,Zr_(0.5)Ba_(0.5)CoO_(x) where x is an amount of O that counterbalancesBa, Zr, and Co cations of the metal oxide, TiO₂:CeO₂, ZrO₂, Y₂O₃:ZrO₂,ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount of O thatcounterbalances Zr, Ba, and V cations of the metal oxide, TiO₂:ZrV₂O₇,each optionally comprising a cationic dopant comprising an oxide ofBa²⁺, Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺, Cu²⁺, Ni²⁺, Fe³⁺, and any combinationthereof; the metal oxide nanoparticle is selected from ZrO₂, Y₂O₃:ZrO₂,ZrV₂O₇, TiO₂:ZrV₂O₇, Zr_(0.5)Ba_(0.5)CrO₃, Ba_(0.3)Zr_(0.7)O_(x) where xis an amount of O that counterbalances Ba and Zr cations of the metaloxide, and CeO₂:ZrO₂; and/or the metal oxide nanoparticle can furtherinclude phosphorus.

In any of the above-described engine aftertreatment catalystcompositions, the engine aftertreatment catalyst composition can havefrom 50 wt % to 99.5 wt % (e.g., from 30 wt % to 99.5 wt %) of the metalzeolite; the metal zeolite can be selected from aluminosilicate zeolitesand silico-alumino-phosphate zeolites; the metal zeolite can furtherinclude a cation selected from Pt²⁺, Pd²⁺, Rh²⁺, Cu²⁺, Ni²⁺, and Fe³⁺,and wherein the metal zeolite optionally includes an alkali metal ionselected from Na⁺ and K⁺; the metal zeolite can be selected fromFe-doped aluminosilicate zeolites, Cu-doped aluminosilicate zeolites,Fe- and Cu-doped aluminosilicate zeolites, Fe-dopedsilico-alumino-phosphate zeolites, Cu-doped silico-alumino-phosphatezeolites, and Fe and Cu-doped silico-alumino-phosphate zeolites; themetal zeolite can be selected from Fe-doped chabazite, Cu-dopedaluminosilicate chabazite, and Fe and Cu-doped chabazite; the metalzeolite can be selected from ZSM-5, β-zeolite, SSZ-13 chabazite, andSAPO-34; and/or the metal zeolite can be SAPO-34. In some embodiments,the metal zeolite is Fe and/or Cu-doped silico-alumino-phosphatezeolite, and Fe- and/or Cu-doped aluminosilicate zeolite, incombination.

In any of the above-described engine aftertreatment catalystcompositions, the catalyst composition can have a thermal resistance ofup to 600° C.; and/or the catalyst composition can have a BET surfacearea of at least 200 m²/g.

Embodiments of the engine aftertreatment catalyst compositions of thepresent disclosure can be a diesel oxidation catalyst, a dieselparticulate filter catalyst, a selective catalytic reduction catalyst, aurea hydrolysis catalyst, and/or an ammonia oxidation catalyst.

The urea hydrolysis catalyst can have a NO_(x) conversion efficiency ofat least 10%, when coated onto a surface of an impact static mixer, andwherein the urea hydrolysis catalyst is capable of decomposing urea toproduce ammonia reductant in a diesel engine exhaust stream. The ureahydrolysis catalyst can bind and oxidize SCR catalyst poisons, such ashydrocarbons, sulfur, or a combination thereof. The urea hydrolysiscatalyst can be a sacrificial catalyst.

In the above-described method of reducing NO_(x), the catalyst supportstructure can be selected from a ceramic monolith and a metallicsubstrate; the catalyst composition is capable of decomposing ureadeposits; and/or the catalyst composition increases NO_(x) reductionunder cold start conditions.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisdisclosure will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1A is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 1B is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 1C is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 1D is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 1E is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 1F is a block diagram of an example an aftertreatment system closecoupled to an internal combustion engine with a DOC (POC) upstream of aSCRF.

FIG. 2 is graphical representation of an embodiment of a particle of aprimary catalyst, showing mesopores and catalytic surfaces within theparticle.

FIG. 3 is graphical representation of a mesoporous space within a hybridbinary catalyst (HBC) particle.

FIG. 4 is a schematic illustration of oxidation/reduction reaction ondiscrete sites within and/or on the surface of an HBC particle.

FIG. 5 is a block diagram of an example of an aftertreatment systemcoupled to an internal combustion engine.

FIG. 6A is a scanning electron micrograph of an embodiment 13-Zeolitebefore hybridization with Ba_((0.4))Zr_((0.6))O₃ nanoparticles.

FIG. 6B is a scanning electron micrograph of an embodiment β-Zeoliteafter hybridization with Ba_((0.4))Zr_((0.6))O₃ nanoparticles.Relatively uniform distribution of nanoparticles was facilitated by theuse of surfactant poly(ethyleneglycol-ran-polypropyleneglycol) in thehybridization of the Zr and Ba precursors to the β-zeolite particles.See also Table 2, item 8, below.

FIG. 7 is a scanning electron micrograph of an embodiment of a Type-AHBC based on mesoporous chabazite SSZ-13 (Si/Al=12), with ZrO₂nanoparticles.

FIG. 8 is a scanning transmission electron micrograph of an embodimentof a Type-A HBC based on mesoporous SSZ-13 (Si/Ai=12)/ZrO₂. Elementalmapping of the Type-A mesoporous SSZ-13 (Si/Ai=12) Hybrid binarycatalyst with ZrO₂ nanoparticles (2-5 nm diameter) revealed the presenceof the elements silicon (Si) and aluminum (Al) in the metal oxide phase(as well as in the zeolite phase). This presents clear evidence of thecovalent reaction between the precursors with zeolite surface groupsduring the hybridization process. In addition, this has been verified byelectron energy loss spectroscopy (EELS) analysis. The 2-5 nm diametercrystalline metal oxide (SCO phase) particles are arranged in adiscontinuous network across the entire internal and external surfacesof the zeolite crystal.

FIG. 9 is a scanning electron micrograph of structural characteristicsof an embodiment of a HBC of the present disclosure, SSZ-13 chabaziteHBC with zirconium-barium mixed metal oxide showing the 2-5 diametercrystalline metal oxide (SCO phase) particles arranged in adiscontinuous network across the entire zeolite surface.

DETAILED DESCRIPTION

The present disclosure describes hybrid binary catalysts (HBCs) that canbe used in engine aftertreatment catalyst compositions. The HBCs providesolutions to the challenges facing emissions control. In general, theHBCs include a primary catalyst that can be a highly porous particle anda secondary catalyst. The secondary catalyst coats the surfaces (e.g.,the internal porous surface and/or the external surface) of the primarycatalyst. The syntheses described herein of the HBCs provide a primarycatalyst whose entire surface, or portions thereof, are coated withdiscrete and identifiable crystals of the secondary catalyst. Thecrystals can have a maximum dimension of from 1 to 5 nm.

The HBCs of the present disclosure can include specific chemicalelements that possess the desired electronegativities for the variouschemical reactions that occur in an engine aftertreatment system. Table1 shows a list of suitable elements with desirable electronegativityvalues that can be used in the HBCs, as well as the oxidation states ofthese elements that can be present in the HBCs. In some embodiments, theHBCs include Ba (barium), Co (cobalt), Zr (zirconium), and/or P(phosphorus).

TABLE 1 Electronegativity and oxidation states of selected elements fromthe periodic table. Electronegativity Period Group Element (Paulings)Oxidation State 4 Alkaline earth Ca 1 1⁺, 2⁺ 5 Alkaline earth Sr 0.95 2⁺6 Alkaline earth Ba 0.89 1⁺, 2⁺ 3 3A Al 1.61 1⁺, 2⁺, 3⁺, [1⁻, 2⁻, 3⁻] 4ASi 1.90 1⁺, 2⁺, 3⁺, 4⁺, [1⁻, 2⁻, 3⁻, 4⁻] 4 Transition metal Sc 1.36 1⁺,2⁺, 3⁺ Transition metal Ti 1.54 2⁺, 3⁺, 4⁺ [1⁻, 2⁻] Transition metal V1.63 2⁺, 3⁺, 4⁺, 5⁺ [3⁻] Transition metal Cr 1.66 1⁺, 2⁺, 3⁺, 4⁺, 5⁺, 6⁺[1⁻, 2⁻, 4⁻] Transition metal Mn 1.56 2⁺, 3⁺, 4⁺, 5⁺, 6⁺, 7⁺ [1⁻, 2⁻,3⁻] Transition metal Fe 1.83 2⁺, 3⁺, 4⁺, 5⁺, 6⁺ [1⁻, 2⁻, 4⁻] Transitionmetal Co 1.88 2⁺, 3⁺, 4⁺, 5⁺ [3⁻] Transition metal Ni 1.91 2⁺, 3⁺, 4⁺[1⁻, 2⁺] Transition metal Cu 1.9 1⁺, 2⁺, 3⁺, 4⁺ [2⁻] Transition metal Zn1.65 1⁺, 2⁺ [0, 2⁻] 5 Transition metal Y 1.22 1⁺, 2⁺, 3⁺ Transitionmetal Zr 1.33 1⁺, 2⁺, 3⁺, 4⁺ [2⁻] Transition metal Nb 1.6 1⁺, 2⁺, 3⁺,4⁺, 5⁺ [1⁻, 3⁻] Transition metal Mo 2.16 1⁺, 2⁺, 3⁺, 4⁺, 5⁺, 6⁺ [0, 1⁻,2⁻, 4⁻] Transition metal W 1.7 1⁺, 2⁺, 3⁺, 4⁺, 5⁺, 6⁺ [0, 1⁻, 2⁻, 4⁻] 6Lanthanide Ce 1.12 1⁺, 2⁺, 3⁺, 4⁺ 3 5A P 2.19 1⁺, 2⁺, 3⁺, 4, 5⁺ [1⁻, 2⁻,3⁻]

The catalysts of the present disclosure provide one or more of thefollowing benefits:

(1) The catalysts include a refractory metal oxide that is abundant andrelatively low cost, durable and with relatively low oxidative power(e.g., ZrO₂).

(2) The catalysts use dopants to create oxygen vacancies in the crystallattice and at the surfaces of metal oxide (e.g., zirconium dioxide).The dopants (e.g., Ba²⁺, Ca²⁺, or Sr²⁺) are relatively low in cost andhave reductive power that can counterbalance the oxidative power of themetal oxide, while positively impacting NO_(x) storage on the surface.

(3) The catalysts incorporate selected high oxidative power species(e.g., Ti, Co, Cr, Mn, Nb, V, Mo, and/or W-containing oxides) into amixed metal oxide structure, to tailor the final oxidative poweraccording to a specific application. The high oxidative power speciescan be employed in different oxidation states as needed. For example, aspecies having high oxidative power (1.5-2.2 Paulings) is useful for DOCapplications, while a species having relatively moderate (1 to <1.5Paulings) to low oxidative power (<1.0 Paulings) is useful for highdurability SCR applications. One major exception is cerium (a lanthanideelement), with electronegativity that falls in the moderate range but isalso very effective for DOC application.

Some considerations for the oxidative properties of the HBC include:

(i) without wishing to be bound by theory, it is believed that theoxidative power of the final (zirconia doped) mixed oxide is important,therefore elements with high Pauling values can be used in SCRapplications at relatively low doping levels. At higher doping levels,the same element can be highly effective in DOC applications.

(ii) without wishing to be bound by theory, it is believed that thevalency of the element plays an important role in the observed oxidativepower. Therefore, selection of a element having a low valence state(e.g., 2+, such as Co²⁺) as a dopant in ZrO₂ can be useful in SCRapplication, while an element having high valence (≥3+) can be morepreferred in DOC applications.

The catalysts incorporate acidic (i.e., anionic) groups, such as PO₄ ²⁻in zirconium phosphate, VO₄ ³⁻ in zirconium vanadate, ZrO₃ ²⁻ in bariumzirconate, and/or Mo₇ ⁶⁻ in zirconium molybdate, which facilitate highbinding capacity for cations that provide catalytic activity inemissions control. For example, Cu²⁺ and/or Fe²⁺ can be used for NO_(x)reduction; and Pt²⁺/Pt⁰, other platinum-group metals (PGMs) and certainbase metals (e.g., Ni²⁺ and Fe³⁺) can facilitate oxidative reactionsrequired for DOC and AMOX catalysts.

The use of phosphorous in the metal oxide composition of the catalystscan modulate oxidative power while imparting a degree of phosphatetolerance to the catalyst.

Definitions

As used herein, “hybridization,” “hybridizing,” or “hybridized” refersto the chemical reaction between precursor molecules with specificelements on the surface of the zeolite, resulting in formation of bonds(e.g., covalent bonds, and/or ionic bonds) between the precursors andelements in the zeolite in the metal oxide nanoparticles. Thehybridization can be verified using scanning transmission electronmicroscopy with elemental analysis and electron energy loss spectroscopy(EELS) microstructural analysis techniques. For example, elementalmapping of metal oxide and any cationic dopants can show an aggregate ofmetal oxide nanoparticle, and Si and/or A1 in the zeolite can be presentin the metal oxide phase, with no zeolite crystal present in thebackground.

Furthermore, STEM studies can indicate that the metal oxide phase iscrystalline. Therefore, it is reasonable to assume that theincorporation of Si and A1 into the metal oxide phase is by way ofcovalent and/or ionic bonds in the ZrO₂ crystal lattice. Without wishingto be bound by theory, it is believed that a metal oxide precursor firstforms a coordination bond with the surface atoms of a zeolite (i.e., Si,Al, and/or P), which is facilitated by the use of a chelating agent,such as urea, in the reaction mixture. The formation of thiscoordination complex causes disruptions in the crystal structure nearthe surface. Therefore, a certain degree of deconstruction of thezeolite surface layer(s) occurs to release Si, Al, and/or P forincorporation into the metal oxide phase as it forms.

As used herein, “oxidative power” is defined as the temperature at which50% of the CO is oxidized to CO₂ when a simulated exhaust streamincluding nitric oxide (600 ppm), ethylene (75 ppm C₂H₄), CO (300 ppm),oxygen (10%), carbon dioxide (5.6%), water (6%), and nitrogen (thebalance of simulated exhaust stream), is exposed to a catalyst (e.g., ametal oxide catalyst) at a space velocity of 60,000 hr⁻¹ in a reverselight off study (starting at 600° C., to a temperature of 160° C.). Asan example, a metal oxide with a relatively low oxidative power has a(T₅₀CO) of >600° C. (e.g., ZrO₂), while a metal oxide with relativelyhigh oxidative power has a (T₅₀CO) of <500° C.

As used herein, “reductive power” refers to the ability to enhance theNO_(x) storage property to enhance NO_(x) conversion.

As used herein, “microporous” refers to material having pores of amaximum pore dimension of up to 2 nm, “mesoporous” refers to a materialhaving pores of a maximum pore dimension of from 2 to 50 nm, and“macroporous” refers to a material having pores of a maximum poredimension of greater than 50 nm.

As used herein, “significantly” or “substantially” refers to greaterthan 90% (e.g., greater than 95%, or greater than 98%).

As used herein, “about” refers to +5% (e.g., +3%) of a given value.

As used herein, a selective catalytic oxidation (SCO) catalyst is acatalyst that facilitates:

-   -   (i) Formation of NO₂ species in situ by the reaction of        NO+½O₂→NO₂, to serve as reactive intermediates from nitrogen        oxides in the exhaust stream, without significantly oxidizing        NH₃ into N₂O. For embodiments of the catalysts of the present        disclosure, even if NH₃ oxidation occurs, in some instances the        primary product is N₂, which is a desirable outcome.    -   (ii) Hydrocarbon oxidation at considerably lower temperatures,        for example, the oxidation of longer chain unsaturated        hydrocarbons such as propylene.

As used herein, a selective catalytic reduction (SCR) catalyst is acatalyst that catalyzes the reduction of NO_(x) to nitrogen and water.

As used herein, a urea hydrolysis catalyst is a catalyst that hydrolyzesurea and isocyanic acid (HNCO) with minimal or zero formation of highmolecular weight aromatic (HMAr) compounds such as cyanuric acid,ammilide, ammeline, and/or melamine.

As used herein, a DPF catalyst is a catalyst that captures sootparticles and contains PGM for NO₂-make to facilitate soot lightoff atrelatively low temperatures (e.g., <350° C.) for passive soot oxidation.The DPF can also serve as an ash storage device.

As used herein, a DOC is a catalyst that oxidizes gases and othervolatile particulates from the engine exhaust, including hydrocarbons,CO and NO (which is oxidized to make NO₂, made possible by therelatively high PGM loading.

As used herein, an ammonia oxidation (AMOX) catalyst is a catalyst thatincludes a layer of PGM (such as a DOC), covered by a SCR catalystlayer, which is located after a SCR to carry out dual functions of (1)reducing NO_(x), and (2) scavenge excess NH₃ and selectively oxidize NH₃to N₂, thus avoiding NH₃ slip.

As used herein, a 4-way catalyst is a catalyst that can serve the rolesof a DOC, DPF catalyst, SCR catalyst, urea hydrolysis catalyst, and AMOXcatalyst concurrently.

HBC Structure

As discussed above, in general, the HBCs include a primary catalyst thatcan be a highly porous particle and a secondary catalyst. The secondarycatalyst is hybridized to the surfaces (e.g., the internal poroussurface and/or the external surface) of the primary catalyst. In someembodiments, referring to FIG. 2, the primary catalyst 300 is a metalzeolite. The metal zeolite has a plurality of metal oxide secondarycatalyst nanoparticles, which is a mixed crystal structure containingelements (e.g., Si and/or Al, or Si and Al) from the primary catalyst onthe metal zeolite's inner and/or outer surface.

The metal zeolite can have a large surface area provided by a variety ofpores, such as micropores 310, mesopores 320, and macropores 330. Themicropores have a maximum pore dimension of up to 2 nm. The mesoporeshave a maximum pore dimension of from 2 to 50 nm. The macropores have amaximum pore dimension of greater than 50 nm. In some embodiments, themacropores are the spaces between particles of primary catalyst 300.

Without wishing to be bound by theory, it is believed that the poresprovide access for penetration of a secondary catalyst precursor intothe primary catalyst, such that the secondary catalyst can form byincorporating structural elements at the surface of the primary catalystand thereby crystallize in well-dispersed discrete locations within theprimary catalyst. The higher surface area afforded by pores allows fordecreased diffusion resistance and lower pressure difference for anexhaust gas that is to be treated by the HBC; resulting in greater fueleconomy. A further advantage of secondary catalyst-containing primarycatalyst is the sustained activity that can be afforded by the HBC underconditions where soot/ash covers the outer surfaces of a catalystparticle, which would otherwise poison the catalyst; however, with theHBCs of the present disclosure, the likelihood of poisoning is decreasedbecause the soot/ash cannot access the inner surface of the primarycatalyst, which is covered by a dispersion of a secondary catalyst.Thus, the combination of a well-dispersed secondary catalyst on aprimary catalyst can be resistant to formation of soot and ash. Thewell-dispersed secondary catalyst also provides highly reactivecatalytic sites that can operate in a synergistic manner with theprimary catalyst. For example, the secondary catalyst (e.g., a metaloxide) can adsorb NO and rapidly convert the NO to NO₂, which reacts inthe presence of NH₃ on an adjoining primary catalyst site (e.g., a metalzeolite) to produce N₂. Because the secondary catalyst is welldispersed, a large surface area of catalytically active sites can beprovided, with enhanced catalytic activity.

Without wishing to be bound by theory, it is believed that the HBCs ofthe present disclosure have cation loading by the metal oxide phase ofHBC is dependent on both the amount of metal oxide phase present, aswell as the composition of the metal oxide phase. The cation loadingcapacity can play an important role in platinum group metal (PGM)binding to obtain highly distributed, high activity catalytic centers,which can translate into lower PGM loadings, reduced tendency fordeactivation by sintering, and reduced overall cost.

Without wishing to be bound by theory, it is believed that the HBCsprovide different types of active sites that are located in closeproximity to one another within and/or on a HBC particle. For example,referring to FIG. 3, mesopores 400 can include primary catalyst activesites 410 in close proximity to hybridized secondary catalyst activesites 420. At the hybridized secondary catalyst active sites 420, thesecondary catalyst is hybridized to the surface of the primary catalyst.

The different types of active sites can provide combined catalyticfunctionalities, faster reaction kinetics, synergy for high performancecatalyst activity, and/or improved catalyst durability. In someembodiments, the different types of active sites can allow for rationalcatalyst design for SCR, DOC, or other catalysts in an EAS; and/or canallow for compact and lightweight EAS. Without wishing to be bound bytheory, it is believed that faster reaction kinetics result from theincreased number and close proximity of the catalyst active sites inHBCs, such that multiple catalytic reactions can occur in closeproximity to one another both in time and space. For example, a SCRcatalyst and a selective catalytic oxidation (SCO) catalyst can bespaced apart in the angstrom range in a HBC, which is closer in distanceby 2 to 3 orders of magnitude compared to physically mixed particles ofa SCR and SCO catalyst, as described, for example, in U.S. patentapplication Ser. No. 14/935,199.

Without wishing to be bound by theory, it is also believed that improvedcatalyst durability can be achieved with a HBC due to combination ofproperties of the components of the HBC. For example, a highly oxidativesecondary catalyst can be combined with a high temperature-tolerantprimary catalyst in an appropriate ratio to achieve a HBC that has bothhigh oxidative properties and temperature tolerance.

Without wishing to be bound by theory, it is believed that the primaryand secondary catalysts can act in synergy with respect to one anotherwhen catalyzing the decomposition of exhaust gases, where the primaryand secondary catalysts can both participate in a redox reaction asillustrated in FIG. 4, with one catalyst acting as a reducing agent(e.g., an anode) and the other catalyst acting as an oxidizing agent(e.g., a cathode). The redox reaction shown in FIG. 4 is a spontaneousand self-perpetuating process that occurs at adjacent active sites,where mass transfer limitations are minimal due to the close proximityof the active sites. The HBC components can be selected to possess ionexchange/binding properties to enable ion transport between sites bothon the surface and in the bulk material. For example, doping of ZrO₂with Y³⁺ cationic dopant creates lattice vacancies that permit O²⁻transport through the bulk. On the other hand, dopants such as Ba²⁺ cancreate lattice vacancies (e.g., in BaZrO₃) that permit cation binding,and hence transport of cations (e.g., H₃O⁺) between reduction/oxidationsites in the bulk material.

In some embodiments, the HBCs of the present disclosure have a primarycatalyst that includes one or more metal zeolites. In some embodiments,the metal zeolite is aluminosilicate zeolites and/orsilico-alumino-phosphate zeolites. For example, the metal zeolite can bean aluminosilicate zeolite. In certain embodiments, the metal zeolite isa silico-alumino-phosphate zeolite. In some embodiments, the one or moremetal zeolites further include a cation such as Pt²⁺, Pd²⁺, Rh²⁺, Cu²⁺,Ni²⁺, and/or Fe³⁺ in the zeolite active sites. In certain embodiments,the metal zeolite also includes an alkali metal ion such as Na⁺ and K⁺in the zeolite active sites to effectively neutralize (or cap) residualacid sites in the zeolite after doping with the desired catalytic metalion. In certain embodiments, the one or more zeolite does not includeany cations.

In some embodiments, the HBCs can include from 0.5 wt % (e.g., from 1 wt%, from 10 wt %, from 20 wt %, from 30 wt %, from 40 wt %, from 50 wt %,from 60 wt %, from 70 wt %, from 80 wt %, or from 90 wt %) to 99.5 wt %(e.g., to 90 wt %, to 80 wt %, to 70 wt %, to 60 wt %, to 50 wt %, to 40wt %, to 30 wt %, to 20 wt %, to 10 wt %, or to 1 wt %) of the one ormore metal zeolites. In certain embodiments, the HBCs can include from10 wt % to 50 wt % (e.g., from 20 wt % to 40 wt %, from 30 wt % to 50 wt%, or about 30 wt %) of the one or more metal zeolites.

In some embodiments, the metal zeolite is a Fe-doped aluminosilicatezeolite, a Cu-doped aluminosilicate zeolite, a Fe- and Cu-dopedaluminosilicate zeolite, a Fe-doped silico-alumino-phosphate zeolite, aCu-doped silico-alumino-phosphate zeolite, and/or a Fe and Cu-dopedsilico-alumino-phosphate zeolite. In certain embodiments, the metalzeolite is a Fe-doped chabazite, a Cu-doped aluminosilicate chabazite,and/or a Fe and Cu-doped chabazite. In certain embodiments, the metalzeolite is a Fe and/or Cu-doped silico-alumino-phosphate zeolite, andFe- and/or Cu-doped aluminosilicate zeolite in combination. In certainembodiments, the metal zeolite is ZSM-5 and/or β-zeolite. In certainembodiments, the metal zeolite is a chabazite. In certain embodiments,the metal zeolite is SSZ-13 or SAPO-34.

In some embodiments, the HBCs of the present disclosure have a secondarycatalyst that includes one or more metal oxides. The metal oxides can bein the form of nanoparticles, having a maximum dimension of from 0.1 nm(e.g., from 1 nm, from 5 nm, from 10 nm, from 20 nm, from 30 nm, or from40 nm) to 50 nm (e.g., to 40 nm, to 30 nm, to 20 nm, to 10 nm, to 5 nm,or to 1 nm). In certain embodiments, the metal oxides in the form ofnanoparticles have a maximum dimension of from 1 nm to 5 nm (e.g., from1 nm to 4 nm, from 2 nm to 5 nm, from 3 nm to 5 nm; about 3 nm). Thesecondary catalyst can be imaged via electron microscopy, and can bediscrete nanoparticles located on the primary catalyst or withinmesopores of the primary catalyst.

The one or more metal oxides of the secondary catalyst of the HBCs caninclude, for example, cerium oxide, titanium oxide, zirconium oxide,aluminum oxide, silicon oxide, hafnium oxide, vanadium oxide, niobiumoxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide,ruthenium oxide, rhodium oxide, iridium oxide, nickel oxide, bariumoxide, yttrium oxide, scandium oxide, calcium oxide, barium oxide,manganese oxide, lanthanum oxide, strontium oxide, cobalt oxide, copperoxide, iron oxide, and/or any combination thereof. In some embodiments,the one or more metal oxides of the HBCs are zirconium oxide, vanadiumoxide, cerium oxide, manganese oxide, chromium oxide, cobalt oxide,titanium oxide, tungsten oxide, barium oxide, and/or any combinationthereof. In certain embodiments, the one or more metal oxides of the HBCinclude zirconia, ceria, vanadia, chromium oxide, barium oxide andniobium oxide.

In some embodiments, the one or more metal oxides of the secondarycatalysts of the HBCs further include a cationic dopant. For example,the cationic dopant can include an oxide that includes Mg²⁺, Cu²⁺Cu+,Ni²⁺, Ti⁴⁺, V⁴⁺, Nb⁴⁺, Ta⁵⁺, Cr³⁺, Zr⁴⁺, Mo³⁺, W⁶⁺, W³⁺, Mn²⁺, Fe³⁺,Zn²⁺, Ga³⁺, Al³⁺, In³⁺, Ge⁴⁺, Si⁴⁺, Co²⁺, Ni²⁺, Ba²⁺, La³⁺, Ce⁴⁺, Nb⁵⁺,Sr²⁺, Pt²⁺, Pd²⁺, and/or Rh^(2+.) In certain embodiments, the cationicdopant is an oxide that includes Pt²⁺, Pd²⁺, and/or Rh²⁺.

In certain embodiments, the one or more metal oxides of the secondarycatalysts of the HBCs include a cation of one or more of the followingelements: Ca, Sr, Ba, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb,Mo, W, Ce, and/or P, which, with the exception of P, can be in the formof an oxide, and/or in the form of dopants in a metal oxide of thesecondary catalyst. In some embodiments, when in the form of dopants,the dopant cations is achieved by incipient wetness impregnation and isbound by the anion exchange characteristics of the metal oxide, asdescribed, for example, in Example 4, below. In some embodiments, one ormore metal oxides of the secondary catalysts of the HBCs include acation of one or more of Ba, Co, Zr, and/or P.

The HBCs of the present disclosure provide flexibility in theircompositions. For example, the composition can be changed by adjustingan oxidative power to address the tradeoff between NO_(x) reductionperformance and durability. In some embodiments, the optimal compositioncan be determined for each metal oxide system. The compositionspresented herein illustrate the unique nature of this whole new class ofcatalyst material. In some embodiments, the one or more metal oxides ofthe secondary catalyst of the HBCs are CeO₂:ZrO₂ (i.e., a mixture ofCeO₂ and ZrO₂ having, for example, from 40 wt % to 60 wt % CeO₂,Y₂O₃:CeO₂ (i.e., a mixture of Y₂O₃ and CeO₂, where, in some embodiments,has about 10 wt % of Y₂O₃), BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃,Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of O that counterbalances theZr and Ca cations of the composition, Zr_(0.5)Ba_(0.5)Mn₃O₄,Ba_(0.3)Zr_(0.7)O_(x) (Ba_(0.3)Zr_(0.7) oxide) where x is an amount of Othat counterbalances the Ba and Zr cations of the composition,Zr_(0.5)Ba_(0.5)CrO₃, Zr_(0.5)Ba_(0.5)CoO_(x) (including higheroxidation states of cobalt oxide) where x is an amount of O thatcounterbalances the Zr, Ba, and Co cations of the composition, Zroxides, and/or TiO₂:CeO₂ (i.e., a mixture of TiO₂ and CeO₂), eachoptionally including a cationic dopant that is an oxide that includesBa²⁺, Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺, Cu²⁺, Ni²⁺, and Fe³⁺. In some embodiments,the metal oxide of the secondary catalyst in the HBCs is ZrO₂,Y₂O₃:ZrO₂, ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount ofO that counterbalances the Zr, Ba, and V cations of the composition,Zr_(0.7)Ti_(0.3)VO_(x) where x is an amount of O that counterbalancesthe Z, Ti, and V cations of the composition, Zr_(0.7)Ba_(0.3) oxide,and/or CeO₂:ZrO₂. In certain embodiments, while CeO₂ has higheroxidative power, ZrO₂ is selected instead as the secondary catalystbased upon both durability consideration and its ability to be modifiedby doping with strong oxidizing species (such as Mn₃O₄, CoO₃, V₂O₇,CrO₃, WO₂, MoO₂, NiO, Fe₃O₄, (HPO₄)²⁻, any combination thereof, and thelike), in addition to modifiers such as BaO, which can enhance NO_(x)storage.

In some embodiments, the HBC do not include a cationic dopant. In someembodiments, the HBC consists of a metal oxide including a cationicdopant. In certain embodiments, the HBC consists of a metal oxide. Insome embodiments, the one or more metal oxides do not include a cationicdopant. In some embodiments, the secondary catalyst consists of a metaloxide including a cationic dopant. In certain embodiments, the secondarycatalyst consists of a metal oxide.

In some embodiments, the HBCs can have from 0.5 wt % (e.g., from 1 wt %,from 10 wt %, from 20 wt %, from 30 wt %, from 40 wt %, from 50 wt %,from 60 wt %, from 70 wt %, from 80 wt %, or from 90 wt %) to 99.5 wt %(e.g., to 90 wt %, to 80 wt %, to 70 wt %, to 60 wt %, to 50 wt %, to 40wt %, to 30 wt %, to 20 wt %, to 10 wt %, or to 1 wt %) of the one ormore metal oxide secondary catalysts.

The HBCs of the present disclosure can have a variety of desirableproperties.

For example, the HBCs can have a thermal resistance of up to 600° C. Asused herein, “thermal resistance” refers to the ability of a catalyst toretain catalytic activity even with repeated exposure of up to 600° C.over extended periods of time (e.g., 100 hours).

The HBCs can offer combinations of desirable catalytic properties. Forexample, a SCR catalyst including Cu and/or Fe-doped zeolite-based HBCshaving one crystalline metal oxide on an outer surface or within thezeolite mesopores can be additionally modified with a non-crystallineselective catalytic oxidation (SCO) catalyst by impregnation of anapplied washcoat using an appropriate precursor solution (such as nickelsulfate heptahydrate), without the need to mix separate SCR and SCOparticles.

High SCR:SCO ratios can be achieved with equivalent or higher SCOsurface area for enhanced NH₃ storage capacity with a lower mass ofmetal oxide, compared to that for a physical mixture of primary andsecondary catalyst particles. The SCO phase can be tailored to obtainoptimal oxidative power (e.g., with CrO₃) independently of storagecapacity for reactants such as NH₃ or for NO_(x) (e.g., with BaO). Insome embodiments, the HBCs of the present disclosure provides theability to design and construct all major types of heavy duty dieselaftertreatment catalyst, such as a 4-way catalyst, described below.

The HBCs of the present disclosure can have tailored cold start and coldFTP cycle performance. As used herein, cold start conditions refer tothe first 400 seconds after key-on as the temperature of theaftertreatment increases to achieve the optimal 350-450° C. range forNO_(x) reduction. As used herein, an “FTP cycle” refers to an EPAFederal Test Procedure, commonly known as FTP-75 for a city drivingcycle. The HBCs can provide NO_(x) reduction catalyst compositions witheffective performance in low or zero NO₂ conditions, such as when aclose couple SCR is employed without a DOC upstream, or when a SCRF isused and soot oxidation reaction competes with the fast SCR reaction forthe available NO₂. A DOC is used to produce sufficient NO₂ to optimallyobtain a NO₂! NO_(x) ratio of unity. As NO₂! NO_(x) declines, so doesthe NO_(x) reduction efficiency, due to the critical role played by NO₂in the “fast” SCR reaction (see reaction (3), above).

In some embodiments, the HBCs of the present disclosure have a BETsurface area of at least 200 m²/g (e.g., at least 300 m²/g, at least 400m²/g, or at least 500 m²/g).

Without wishing to be bound by theory, it is believed that HBC with alarge BET surface area has greater catalytic activity compared to an HBCwith a smaller BET surface area.

In some embodiments, the HBC has increased catalytic activity comparedto a catalyst including metal oxide nanoparticles and a non-porous metalzeolite. As an example, a HBC including Cu-doped chabazite (CuSSZ-13)hybridized with nanocrystals of Ba_(0.3)Zr_(0.7)O_(x) (where x is anamount of O that counterbalances the Zr and Ba cations of thecomposition) has a T₅₀ of 240° C. for NO_(x) reduction efficiency withno NO₂ in the feed stream, which compares favorably with a reference2013 commercial SCR control catalyst T₅₀ of 300° C. (see Example 2,infra). The 60° C. lower lightoff temperature for NO_(x) reduction forthis HBC translates to the possibility of significant improvements overconventional SCR catalysts in cold start and cold FTP performance.

HBCs as Engine Aftertreatment Catalysts

The HBCs of the present disclosure are highly versatile and can be used,for example, as a diesel oxidation catalyst (DOC), a diesel particulatefilter (DPF) catalyst, a selective catalytic reduction (SCR) catalystthat can be used in a conventional SCR and/or in a SCRF configuration, aurea hydrolysis catalyst, and/or an ammonium oxidation (AMOX) catalyst.

As an example, a HBC-based DOC can have a zeolite primary catalyst ofrelatively high thermal resistance (e.g., small pore zeolites such asSSZ-13), while possessing good hydrocarbon (HC) and NO_(x) storagecapacities. As used herein, “storage capacity” refers to the ability ofa catalyst to adsorb amounts of the reactant species on the surface as afirst step in the heterogeneous catalysis process. Therefore, it isunderstood by a person of ordinary skill in the art that good storagecapacities (i.e., good adsorptive properties) are desirable for goodreaction rates.

Storage capacities can be modified by exchanging cations (e.g., Pt²⁺,Pd²⁺, Rh²⁺, Ru²⁺, Cu²⁺, Ni²⁺, and/or Fe³⁺) into the active sites of thezeolite. The secondary catalyst in the HBC-based DOC can be a metaloxide that has relatively high oxidative power (e.g., CeO₂:ZrO₂, Y-dopedCeO₂, BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃, Zr_(0.8)Co_(0.2)O₄, CeO₂—Mn₃O₄,Ce/Co/Zr, and/or TiO₂—CeO₂), modified with cations that can enhanceNO_(x) storage (e.g., Ba²⁺), as well as enhance NO_(x), CO, and HCoxidation compared to conventional Cu-zeolite-based SCR catalysts (e.g.,Pt²⁺, Pd²⁺, Rh²⁺, Cu²⁺, Ni²⁺, and/or Fe³⁺).

In some embodiments, a HBC-based DOC includes a zeolite primary catalystwith a metal oxide secondary catalyst such as ZrV₂O₇;Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount of O thatcounterbalances the Zr, Ba, and V cations of the composition, and/orCe_(0.6)Zr_(0.4), which can be further modified with Pt²⁺, Pd²⁺, Rh²⁺,Ru²⁺, Cu²⁺, Ni²⁺, Fe³⁺, and/or Ba²⁺. In some embodiments, complex oxidescan have non-stoichiometric amounts of oxygen to lattice oxygenvacancies due to doping of the foreign cation into the latticestructure. Relatively large pore size zeolite primary catalysts (e.g.,β-zeolite) are preferred due to their enhanced HC storage abilitycompared with small pore zeolites (e.g., chabazite).

The HBC-based DOC can be located upstream of the SCR. An importantvariant of a DOC is a partial oxidation catalyst (POC), which is aDOC-like catalyst applied to a particle filter that enables theoxidation of volatile organic compound (VOC) components of particulatematter in the exhaust gas while allowing larger particles to passthrough to the DPF. The POC can serve the normal function of the DOC,and may preferentially be located upstream of a SCRF, to reduce as muchas 50% of the soot reaching the SCRF; thus almost doubling the ashcleaning interval for a SCRF, which is otherwise considerably less whencompared to a conventional DPF.

In some embodiments, DPF catalysts are constructed from HBCs asdescribed above for the DOC. A conventional DPF is located downstream ofthe DOC and upstream of the SCR, and is made of a particle filtersubstrate with a Pt/Pd-based catalyst coating that can oxidize NO_(x) togenerate NO₂; oxidize residual HC that can pass through the DOC;passively and/or actively oxidize soot in regenerating the DPF to formash for storage; and provide a higher storage capacity, which results ina longer cleaning interval and a lower maintenance cost for the EAS. Insome embodiments, as with DOC catalysts, the HBC-based DPF catalystincludes HBC catalysts having low or zero Pt/Pd content.

In some embodiments, an HBC-based SCR catalyst is composed of zeoliteswith relatively high thermal resistance (e.g., small micropores)zeolites such as SSZ-13 and SAPO-34), which has been doped with Cu²⁺and/or Fe³⁺; with or without an alkali metal ions such as Na⁺ or K⁺,which can occupy residual Bronsted Lowry sites of the zeolite structurebut serve no direct catalytic function. The secondary catalyst in theHBC-based SCR catalyst can be a metal oxide that has an oxidative powerthat can be tailored based upon the trade-off between NO_(x) reductionperformance and durability, such as ZrO₂ or Y-doped ZrO₂, ZrV₂O₇,TiO₂/ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount of O thatcounterbalances the Zr, Ba, and V cations of the composition,TiO₂:ZrV₂O₇ (e.g., Zr_(0.7)Ti_(0.3)VO_(x) where x is an amount of O thatcounterbalances the Zr, Ti, and V cations of the composition),Zr_(0.7)Ba_(0.3) oxide, and/or CeO₂:ZrO₂. The HBC-based SCR catalyst canbe employed in a conventional SCR and/or in a SCRF configuration.

In certain embodiments, the HBC-based SCR catalyst includes a metaloxide secondary catalyst such as CeO₂:ZrO₂ (i.e., a mixture of CeO₂ andZrO₂, such as from 40% to 60 wt % Ce in Zr), Ce_(0.6)Zr_(0.4)O_(x) wherex is an amount of O that counterbalances the Zr and Ce cations of thecomposition, Y₂O₃:CeO₂ (i.e., a mixture of Y₂O₃ and CeO₂), BaZrO₃,Zr_(0.8)Sr_(0.2)CoO₃, Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of Othat counterbalances the Zr and Ca cations of the composition,Zr_(0.5)Ba₀₅Mn₃O₄, Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of O thatcounterbalances the Zr and Ba cations of the composition,Zr_(0.5)Ba_(0.5)CrO₃, Zr_(0.5)Ba_(0.5)CoO_(x) where x is an amount of Othat counterbalances the Zr, Ba, and Co cations of the composition(including higher oxidation states of cobalt oxide), Zr oxides and/orTiO₂:CeO₂, ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇, Zr_(0.3)Ba_(0.5)V_(0.6)O_(x) where xis an amount of O that counterbalances the Zr, Ba, and V cations of thecomposition, and/or TiO₂:ZrV₂O₇ (e.g., Zr_(0.7)Ti_(0.3)VO_(x) where x isan amount of O that counterbalances the Zr, Ti, and V cations of thecomposition).

In some embodiments, referring to FIG. 1A, the HBC-based SCR catalystcan be used in a diesel particulate filter in a SCR system 104, such asa wall-flow filter, and particularly the monolithic core of thewall-flow filter. In some embodiments, the HBC-based SCR catalyst canlead to more compact exhaust aftertreatment systems. For example,referring to FIG. 1B, an exhaust aftertreatment system 124 includes adiesel oxidation catalytic system 196 upstream of a diesel exhaust fluiddoser 202. A selective catalytic reduction on-filter (SCRF) 200 isdownstream of the diesel exhaust fluid doser 202, and SCRF 200 isfollowed by a selective catalytic reduction system 204. The SCRFincludes a diesel particulate filter (DPF) with a catalytic substratehaving an HBC-based SCR catalyst coated thereon, thereby providing acompact SCRF that combines the functions of both a DPF and a selectivecatalytic reduction system. In some embodiments, referring to FIG. 1C,an exhaust aftertreatment system 224 includes a combined dieseloxidation catalytic system (“DOC”) and a diesel particulate filter 296upstream of a diesel exhaust fluid doser 302. Downstream of the dieselexhaust fluid doser 302 is SCRF 300, which includes a DPF with acatalytic core having an HBC-based SCR catalyst loaded thereon. Exhaustaftertreatment system 224 has a DPF both upstream and downstream of themixer and therefore increases the filter capacity. As shown in FIG. 1C,exhaust aftertreatment system 224 is more compact than the exhaustaftertreatment system 124 shown in FIG. 1B.

In certain embodiments, a “close-coupled SCR” with DEF doser may belocated as close to the engine as possible, to obtain optimal reactiontemperature despite reduced exhaust temperatures due to the use of anEGR. Examples of close-coupled SCR configurations are shown in FIGS. 1Dand 1E. These close-coupled SCR configurations employ dual DEF dosers,with a DEF doser upstream of each SCR in the EAS, forming a more complexsystem configuration compared to current EASs, which generally have oneDEF doser. EAS including a close-coupled HBC-based POC upstream of aSCRF is shown in FIG. 1F.

In some embodiments, a HBC-based AMOX catalyst can replace conventionalcatalyst compositions, which typically include a Pt/Pd catalyst washcoaton a flow through substrate, covered by a second Cu or Fe zeolite SCRwashcoat catalyst layer.

The AMOX catalyst is configured to utilize ammonia slip from SCR forNO_(x) reduction, while decreasing the likelihood of NH₃ slip into theenvironment. Preferred embodiment of the HBC-based AMOX catalystinclude, for example, a Cu and/or Fe-doped zeolite primary catalyst withone or more metal oxide secondary catalysts including CeO₂:ZrO₂ (i.e., amixture of CeO₂ and ZrO₂, preferably between 40 wt % to 60 wt % Ce,Y₂O₃:CeO₂ (i.e., a mixture of Y₂O₃ and CeO₂), BaZrO₃,Zr_(0.9)Ca_(0.1)O₂, Zr_(0.8)Sr_(0.2)CoO₃, Zr_(0.5)Ba_(0.2)Mn_(0.3)O₄,Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of O that counterbalances theZr and Ba cations of the composition, Zr_(0.5)Ba_(0.5)CrO₃,Zr_(0.5)Ba_(0.5)CoO_(x) (including higher oxidation states of cobaltoxide, where x is an amount of O that counterbalances Zr, Ba, and Cocations of the composition), Zr oxides and/or TiO₂:CeO₂ (i.e., a mixtureof TiO₂ and CeO₂), ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O_(x)where x is an amount of O that counterbalances the Zr, Ba, and V cationsof the composition, TiO₂:ZrV₂O₇, Zr_(0.7)Ti_(0.3)VO_(x) where x is anamount of O that counterbalances the Zr, Ti, and V cations of thecomposition, and/or Ce_(0.6)Zr_(0.4)O₄. The HBC-based AMOX catalyst canbe further modified with Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺, Cu²⁺, Ni²⁺, Fe³⁺,and/or Ba²⁺.

In certain embodiments, the HBC-based AMOX catalyst includes a firstcatalyst layer that includes a metal zeolite primary catalyst havingmesopores and metal oxide secondary catalyst crystalline nanoparticleshybridized to the surface of the metal zeolite. The metal zeoliteprimary catalyst can include an aluminosilicate zeolite and/or asilico-alumino-phosphate zeolite. The aluminosilicate zeolite orsilico-alumino-phosphate zeolite can includes a cation such as Pt²⁺,Pd²⁺, Cu²⁺, Ni²⁺, and/or Fe³⁺, and wherein the aluminosilicate zeoliteor silico-alumino-phosphate zeolite optionally includes an alkali metalion selected from Na⁺ and K⁺. The metal oxide secondary catalyst caninclude CeO₂:ZrO₂, Y₂O₃:CeO₂, BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃, CeO₂—Mn₃O₄,Ce/Co/Zr oxides, Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of 0 thatcounterbalances the Zr and Ca cations of the composition,Zr_(0.5)Ba_(0.5)Mn₃O₄, Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of Othat counterbalances Zr and Ba cations of the composition,Zr_(0.5)Ba_(0.5)CrO₃, Zr_(0.5)Ba_(0.5)CoO_(x) (including higheroxidation states of cobalt oxide) where x is an amount of O thatcounterbalances the Zr, Ba, and Co cations of the composition, Zr oxidesand/or TiO₂:CeO₂ (i.e., a mixture of TiO₂ and CeO₂), ZrO₂, Y₂O₃:ZrO₂,ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O₄₋₇, TiO₂:ZrV₂O₇, Zr_(0.7)Ti_(0.3)VO_(x)where x is an amount of O that counterbalances the Zr, Ti, and V cationsof the composition, and/or Ce_(0.6)Zr_(0.4)O₄. The HBC-based AMOXcatalyst can be further modified with Ba²⁺, Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺,Cu²⁺, Ni²⁺, and/or Fe³⁺.

The HBC-based ammonium oxidation catalyst can also include a secondcatalyst layer including a metal zeolite and metal oxide nanoparticleshybridized to the surface. The metal zeolite can include analuminosilicate zeolite and a silico-alumino-phosphate zeolite. Thealuminosilicate zeolite or silico-alumino-phosphate zeolite includes acation selected from Cu²⁺, Ni²⁺, and Fe³⁺, and wherein thealuminosilicate zeolite or silico-alumino-phosphate zeolite optionallyincludes an alkali metal ion selected from Na⁺ and K⁺. The metal oxidenanocrystalline particle is ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇, Zr_((1-x))Ba_(x)oxide (where x is between 3 and 4), BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃,CeO₂—Mn₃O₄, Ce/Co/Zr oxides, BaZrO₃, Zr_(0.9)Ca_(0.1)O₂,Zr_(0.5)Ba_(0.5)Mn₃O₄, Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of Othat counterbalances the Ba and Zr cations of the composition,Zr_(0.5)Ba_(0.5)CrO₃, Zr_(0.5)Ba_(0.5)CoO_(x) (including higheroxidation states of cobalt oxide) where x is an amount of O thatcounterbalances the Zr, Ba, and Co cations of the composition, Zr oxidesand/or TiO₂:CeO₂ (i.e., a mixture of TiO₂ and CeO₂), ZrO₂, Y₂O₃:ZrO₂,ZrV₂O₇, Zr_(0.3)Ba_(0.1)V_(0.6)O₃-7, TiO₂:ZrV₂O₇, Zr_(0.7)Ti_(0.3)VO_(x)where x is an amount of O that counterbalances the Zr, Ti, and V cationsof the composition, CeO₂:ZrO₂, and/or Ce_(0.6)Zr_(0.4)O₄.

In some embodiments, a HBC-based urea hydrolysis catalyst has the samecomposition as a HBC-based SCR catalyst, or has a dramatically reversedratio of zeolite-to-metal oxide (i.e., with the metal oxide secondarycatalyst as the majority species in the HBC). In some embodiments, theHBC includes metal oxide nanoparticles and a metal zeolite. The metalzeolite has metal oxide nanoparticles hybridized on the availablesurfaces.

In certain embodiments, the HBC-based urea hydrolysis catalyst isapplied to the surface of an impact static mixer and has a NO_(x)conversion efficiency of at least 10%.

Hydrolysis Catalyst Washcoat Procedure:

A washcoat slurry including the following can be used to coat a metallicmixer device, which can first be surface roughened by abrasion,degreased with isopropanol and washed with deionized water: HBC (Type B,see below), deionized water; optionally lactic acid; poly(ethyleneglycol-ran-propylene glycol) (e.g., having a molecular weight M_(n) ofabout 2,500); poly(ethylene oxide) (e.g., having a molecular weightM_(v) of about 300,000). Following mixing or milling (such as millingusing a roller mill apparatus), the washcoat slurry can be cooled toroom temperature and applied to a substrate, such as a metallic mixer.After drying for a period of 8-12 hours in air, the coated mixer can bedried in an air oven at about 100-120° C. A second coating can beoptionally applied and the coated mixer can be calcined (e.g., for 1 hrat about 450-650° C.). Relative durability of the coating can bedetermined by weighing before and after applying a blast of N₂ at 70psig.

In some embodiments, a washcoat slurry including the following can beused to coat a metallic mixer device, which has been surface roughenedby abrasion, degreased with isopropanol and washed with deionized water:3.5 g HBC (Type-B) based upon CuZSM-5 zeolite with 35% hybridized ZrO₂;12 g deionized water; 0.3 g lactic acid; 0.3 g poly(ethyleneglycol-ran-propylene glycol) Mn ˜2,500; 0.3 g poly(ethylene oxide) Mv300,000 (all reagents obtained from Sigma-Aldrich). Following extensivemixing in a roller mill apparatus, the slurry was cooled to roomtemperature and applied to the metallic mixer. After drying for a periodof 8-12 hours in air, the coated mixer was dried at 105° C. in an airoven. A second coating was then applied. The washcoat was calcined for 1hr at 450° C. Relative durability of the coating was determined byweighing before and after applying a blast of N2 at 70 psig.

In some embodiments, the DEF is sprayed onto the coated mixer at atemperature of 150° C. to 500° C. for the NO_(x) reduction of dieselengine exhaust. It is believed that the primary function of the ureahydrolysis catalyst is the hydrolytic breakdown of urea, HNCO and otherurea byproducts as rapidly as possible to facilitate NH₃ production; andthat NO_(x) reduction is a secondary function that can contribute toaddressing overall NO_(x) reduction of the EAS. In some embodiments, theurea hydrolysis catalyst can bind and oxidize SCR catalyst poisons, suchas hydrocarbons, sulfur, phosphorus, or a combination thereof. In someembodiments, the urea hydrolysis catalyst can be regenerated. In someembodiments, the urea hydrolysis catalyst is a sacrificial catalyst thatcan irreversibly bind SCR catalyst poisons.

4-Way Catalyst

In some embodiments, a given HBC of the present disclosure replaces theDOC, DPF catalyst, SCR catalyst, optionally used urea hydrolysiscatalyst, and AMOX catalyst that are located in separate compartments inan EAS. Instead, referring to FIG. 5, the HBCs of the present disclosurecan be located in a single compartment 500 and perform the functions ofthe DOC, DPF, SCR, optionally used urea hydrolysis catalyst, and AMOXconcurrently, as a 4-way catalyst. A 4-way catalyst is defined as asingle catalyst packaging based upon an HBC, with the capability ofaddressing the four main functions of an EAS: i.e., the functions of theDOC, DPF, SCR, and AMOX catalysts. In some embodiments, the 4-waycatalyst also performs the functions of the urea hydrolysis catalyst.The advantages associated with the 4-way catalyst include, for example,the 4-way catalyst can provide compact, lightweight and relatively lowcost EAS; can streamline product offering for a global market; can lowermanufacturing cost; and can lower cost of ownership for the customer.

In some embodiments, the EAS has one catalyst, a 4-way catalyst, whichis based upon the HBC platform technology, with specific regions of the4-way catalyst modified to emphasize the specific functionalities: DOCor POC, SCR on DPF filter (SCRF) with a hydrolysis catalyst coated DEFmixer, and optionally SCR with an AMOX, as required. The precisedimensions and relative proportions of the different functionalities inthe 4-way catalyst can be tailored to the specific engine exhaustconditions (e.g., engine out NO_(x) levels).

In some embodiments, the HBC-based 4-way catalyst is copper-dopedchabazite containing zirconium vanadate and doped with Pt²⁺ and Pd²⁺;copper-doped β-zeolite containing barium vanadate and doped with Co²⁺,Pd²⁺, and Rh²⁺; copper-doped ZSM-5 barium zirconate and doped with Co²⁺,Pd²⁺, and Ru²⁺; copper-doped chabazite containing ceria zirconia anddoped with Pt²⁺ and Pd²⁺; and/or copper-doped chabazite containingzirconium barium phosphate and doped with Ni²⁺. In some embodiments, theHBC-based 4-way catalyst is copper-doped chabazite containing zirconiumvanadate and doped with Pt²⁺ and Pd²⁺; copper-doped β-zeolite containingbarium vanadate and doped with Co²⁺, Pd²⁺, and Rh²⁺; copper-doped ZSM-5barium zirconate and doped with Co²⁺, Pd²⁺, and Ru²⁺, copper-dopedchabazite containing ceria zirconia and doped with Pt²⁺ and Pd²⁺; and/orcopper-doped chabazite containing zirconium barium phosphate and dopedwith Ni²⁺.

As an example, a representative 4-way catalyst composition for heavyduty truck application is as follows:

-   -   (i) POC composed of HBC (Type-A), based upon Cup-zeolite        hybridized with 10% Zr_((0.8))Co_((0.19))Ba_((0.01)), and        applied to a 50% particle retention metallic filter substrate.        After calcining, the washcoat is impregnated with Pd (0.1        g/L):Rh (0.5 g/L) catalyst;    -   (ii) Hydrolysis catalyst composition: HBC (Type-B) based upon        Cup-zeolite with 35% hybridized ZrO₂, coated onto a metallic        static mixer that is equipped for electrical heating;    -   (iii) SCRF with a HBC (Type-A) composition of Cu (0.6 wt        %)-chabazite/3% Zr_((0.6))Ba_((0.2))Co_((0.2)) applied to a high        porosity (65%) silicon carbide DPF filter with ≥90% particle        retention;    -   (iv) Optionally Cu (0.6 wt %)-Chabazite/3%        Zr_((0.6))Ba_((0.2))Co_((0.2)) SCR HBC (Type—A) catalyst can be        applied to a flow-through substrate to serve as an extra NO_(x)        reduction step under very high engine-out NO_(x) (e.g., ≥4        g/kW-hr) conditions;    -   (v) The AMOX can be either in a small portion of a flow-through        substrate (downstream of a SCRF), or in a zone coated downstream        portion of a SCR (as described in (iv) above). The catalyst in        each of the two possibilities includes two distinct layers: a        lower layer of HBC catalyst as described in (i) above; and an        upper layer of Cu-chabazite.

In some embodiments, the 4-way catalyst includes CuHBC—SSZ13-ZV/≥0.1 g/L[Pt—Rh—Pd], CuHBC-β-ZB(AP)/≥0.1 g/L [Pt—Rh—Pd], and/orCuHBC-β-ZBCo(AP)≥0.1 g/L [Pt—Rh—Pd] in a DOC (POC) zone; with a ureareductant; CuHBC—SSZ13-ZrO2(AP) in a urea hydrolysis zone;CuHBC—SSZ13-ZB(AP), CuHBC—SSZ13-ZBCo(AP), and/or a blend ofCuSSZ-13/CuHBC—SSZ13-ZB(AP) in a SCR on DPF zone; and CuHBC—SSZ13-ZB(AP)in a SCR/AMOX zone.

In some embodiments, the 4-way catalyst includes CuHBC—SSZ13-ZV/≥0.1 g/L[Pt—Rh—Pd], CuHBC-β-ZB(AP)/≥0.1 g/L [Pt—Rh—Pd], and/orCuHBC-β-ZBCo(AP)≥0.1 g/L [Pt—Rh—Pd] in a DOC (POC) zone; with a hydrogenreductant; CuHBC—SSZ13-ZB(AP), CuHBC—SSZ13-ZBCo(AP)≥0.01 g/L [Pt—Rh—Pd],CuHBC—SSZ13-ZBCo(AP)≥0.01 g/L Pd, and/or CuHBC—SSZ13-ZBCoP(AP)≥0.01 g/LNi in a SCR on DPF zone.

Hybrid Binary Catalyst Preparation

The HBCs of the present disclosure can be synthesized using twodifferent methods, Type-A and Type-B, as outlined below.

Type-A—hybridization between zeolite and metal oxide, followed by copperexchange of the hybrid zeolite/metal oxide material to allow copper tobe loaded on both the zeolite and the metal oxide components of thehybridized material.

Type-B—copper exchange of the zeolite (only) provides Cu-zeolitecrystals, followed by hybridization to covalently link precursormolecules that transform into metal oxide nanoparticles on the surfacesof Cu-zeolite crystals.

Two hybridization procedures can be employed under the Type-A HBCsynthesis method, using metal oxide precursors:

Procedure A—metal oxide precursors were dissolved in acidic aqueoussolution, and the resulting mixture was vigorously stirred to obtainslurry containing zeolite particles. The metal oxide precursors werethen reacted with the zeolite by neutralizing at elevated temperature(typically with 65° C.), with dropwise addition of ammonium hydroxidesolution.

Procedure B—two separate aqueous solutions of reactive precursor wereprepared. The first solution contained the zirconium precursor (andpotentially other precursors in acid solution), along with the zeolitepowder. Upon adding the second solution to the slurry, the hybridizationreaction occurred instantaneously.

Procedure A: Co-Precipitation of Precursors from Acid Solution

In general, procedure A includes mixing metal oxide precursor reagentsin the appropriate stoichiometric proportions in deionized (“DI”) waterwith urea (a chelating agent) to facilitate nucleation of theprecipitating metal oxide(s) at active centers (e.g., Al, Si and Pspecies) on the zeolite crystal surfaces. Examples of precursor reagentsinclude zirconyl chloride octahydrate, ammonium cerium nitrate,potassium permanganate, cobalt nitrate hexahydrate, barium nitrate,ortho phosphoric acid, ammonium molybdate tetrahydrate, calcium nitratetetrahydrate, chromium nitrate, nickel nitrate, potassium permanganate,titanium chloride, tungsten chloride. The selected zeolite can be addedto the clear solution in the powder form, with vigorous stirring toobtain a thoroughly mixed slurry. Optionally, random copolymerpoly(ethyleneglycol-ran-polypropyleneglycol) (i.e., PEO-PPO) can beadded to obtain optimal uniformity of nanoparticles size anddistribution. Heat can be applied (e.g., to about 65° C.) to the slurryand a NH₄OH aqueous solution can be added. The endpoint of thesite-directed hybridization reaction can be established when the sol-gelpoint has been surpassed, which is marked by a dramatic increase inviscosity. Vigorous stirring and continuous heating can allow the highviscosity to decrease, and additional NH₄OH can be added to ensure thatall of the available precursors or reactive moieties have beencovalently bonded to the zeolite surfaces. Where cobalt precursor isemployed, the endpoint is accompanied by a very distinctive color changefrom bright pink to “cobalt blue”. The lack of color in the filtrate andbright cobalt blue color of the retrieved product can be used as a clearindication that most (or all) of the Co²⁺ precursor has beenpreferentially hybridized to the zeolite surface.

The entire mixture can be either briefly quenched in an ice-bath orfiltered while hot. Washing should be conducted with generous quantitiesof deionized water. The solids should be washed, air dried, oven driedat between 105° C.-120° C. (e.g., for 1 hr), and then calcined at 600°C. (e.g., for 1 hr).

Procedure B: Incipient Co-Reactive Precursor Precipitation

In general, for procedure B, two separate aqueous solutions of reactiveprecursor are prepared. A first solution contains zirconium and otherprecursors that only react when neutralized with NH₄OH, along with thezeolite powder to form a slurry. The second solution contained a metaloxide precursor, such as ortho phosphoric acid, sodium vanadate,titanium chloride, and/or ammonium molybdate. When the second solutionis added to the first solution, the metal oxide precursors in the secondsolution reacted instantly with the zirconium precursor(s) in the firstsolution; at room temperature or cooled to below room temperature (e.g.,to −15° C.) to regulate the kinetics of the hybridization reaction toform metal oxide nanoparticles on the zeolite surface. The final NH₄OHneutralization step ensures complete hybridization of the precursors tothe zeolite surface.

Copper sulfate solution in DI water can be used to treat protonatedzeolite, with or without concentrated sulfuric acid adjustment to pH 3.The mixture can be heated at 80° C. for 1-3 hrs, with constant stirring.The copper-exchanged product should be filtered, washed with generousamounts of DI water, air dried, oven dried at between 105° C.-120° C.(e.g., for 1 hr), then calcined at 550° C. (e.g., for 1 hr).

In some embodiments, to make Type-B HBC, copper sulfate solution isfirst incubated with zeolite at 80° C. for 3 hours with vigorousstirring, and processed as described previously for Type-A hybrid binarycatalysts to provide Cu-Zeolite powder, then the Cu-Zeolite powder andmetal oxide precursors can be reacted as described in the copperexchange procedure for Type-A hybrid binary catalysts to achievehybridization. The obtained product can be further treated as describedabove for Type-A hybrid binary catalysts.

In some embodiments, the HBCs of the present disclosure are made byproviding an aqueous solution including a chelating agent (e.g., urea)and a metal oxide precursor such as ZrOCl₂.8H₂O, NaVO₃, BaCl₂,(NH₄)₆Ce^(IV)NO₃)₄, KMnO₄, Co(NO₃)₂ (e.g., cobalt nitrate hexahydrate),Cr(NO₃)₃, CaCl₂, barium nitrate, ortho phosphoric acid, ammoniummolybdate tetrahydrate, calcium nitrate tetrahydrate, nickel nitrate,titanium chloride, tungsten chloride; mixing the aqueous solutionincluding the chelating agent and the metal oxide precursor with azeolite catalyst to provide a metal oxide precursor-coated zeolite; andcalcining the metal oxide precursor-coated metal zeolite to provide theHBC. The HBC include metal oxide nanoparticles bound to the metalzeolite.

While synthetic and naturally occurring zeolites can be employed in thesynthesis of a metal oxide-coated zeolite, mesoporous zeolites areespecially advantageous as they can provide sustained reactivity andenhanced catalytic properties, as previously discussed.

The HBCs can be used and synthesized as catalyst washcoat compositions.In washcoat compositions, the HBCs can have a primary zeolite catalysthaving a maximum particle dimension of less than 1,000 nm. When theprimary zeolite catalyst is a mesoporous particle, very high internalsurfaces areas (e.g., up to about 700 m²/g) are accessible to reactantspecies for synthesizing the metal oxide secondary catalyst directly onthe internal and/or external surfaces to form a HBC in situ. Byutilizing aqueous chemistry, the fully expanded and open pore structureof the highly hydrophilic zeolite can be accessed by the secondarycatalyst precursors throughout the hybridization reaction.

Analysis of the HBCs can be carried out using a variety of techniques,such as inductively coupled plasma (ICP) spectroscopy, which providesaccurate elemental compositions; X-Ray diffraction, which providesinformation on the structural properties (e.g., crystallinity) thatrelates to both composition and durability; BET surface area analysis,which provides both available surface area for catalyst reaction andporosity information, which in turn correlates to access of reactants tothe activity sites; synthetic gas bench (SGB) performance testingprovides emissions control testing information when the catalyst isapplied to a monolith substrate in the form of a washcoat, and whereconditions simulating on-engine test conditions are employed in thistest so that realistic conclusions related to diesel emissions controlcan be drawn from the results; electron energy loss spectroscopy (EELS),which complements ICP by conducting elemental analysis in situ, withouthaving to digest the sample in concentrated acid; scanning electronmicroscopy (SEM) and scanning transmission electron microscopy (STEM)provide in situ microstructural and elemental analysis, depicting thecatalyst in its actual functional state; and/or thermogravimetricanalysis (TGA) and Fourier transform infrared (FTIR) spectroscopy, whichin combination permit analysis of urea thermolysis kinetics.

Method of Using the HBCs

In some embodiments, the HBCs are used for reducing NO_(x) in dieselengine exhaust in a selective catalytic reduction system. During use, anHBC of the present disclosure is exposed to a NO_(x)-containing dieselengine exhaust, where the HBC is disposed on or within a catalystsupport structure. In some embodiments, the catalyst support structureis a ceramic monolith and/or a metallic substrate.

In some embodiments, the HBC is capable of decomposing urea deposits.The HBC can increase NO_(x) reduction under cold start conditions, wherea close coupled SCR is heated to greater than 200° C. within 400 secondsand functions without a DOC upstream.

In some embodiments, the HBC assists in making NO₂ in situ withoutsignificantly oxidizing NH₃ (i.e., by selective catalytic oxidation),while also catalyzing the reduction of NO_(x) (i.e., by selectivecatalytic reduction), such that the HBC simultaneously exhibitsselective catalytic oxidation and selective catalytic reductionproperties. The HBC can be provided in an internal surface areas of thewall-flow filter in a manner such that the distribution or loading ofthe catalyst is generally symmetrical across the wall. The catalyst canincrease the thermal resistance of its individual components, such thatthe components can synergistically interact to provide a more robustcatalyst composition.

Examples Nomenclature Zeolites

-   -   SSZ-13, or SSZ13: Chabazite    -   SAPO-34    -   ZSM-5    -   β: beta zeolite

Metal Oxides

-   -   Z: Zirconium dioxide (ZrO2)    -   ZB: Barium zirconate    -   ZV: Zirconium vanadate (or related compounds)    -   ZP: Zirconium phosphate; or oxides of phosphorus, which serves        as a dopant for ZrO₂    -   B: Barium oxide    -   Co: Cobalt (oxide)    -   Mn: Manganese (oxide)    -   CZ: Ceria-zirconia (also shown as ZCe)    -   Cr: Chromium (oxide)    -   Ca: Calcium    -   AP: “A” refers to the relative amount of metal oxide        precursor(s) employed (see for example Table 5), and “P”        indicates the use of random copolymer        poly(ethyleneglycol-ran-polypropyleneglycol) (i.e., PEO-PPO)]

The following examples are provided to illustrate, not limit, thedisclosure.

Example 1 describes the synthesis and characterization of the HBCs ofthe present disclosure. Example 2 describes the selective catalyticreduction (SCR) performance of exemplary HBCs. Example 3 describesdiesel oxidation catalyst (DOC) properties of HBCs. Example 4 describesUrea Hydrolysis Catalyst Properties of Hybrid Binary Catalysts. Example5 describes embodiments of 4-way catalyst compositions.

Examples Example 1. Hybrid Binary Catalyst Synthesis

The Examples below describe two types of hybrid binary catalysts (HBCs):

Type-A—hybridization between zeolite and metal oxide, followed by copperexchange of the hybrid zeolite/metal oxide material to allow copper tobe loaded on both the zeolite and the metal oxide components of thehybridized material.

Type-B—copper exchange of the zeolite (only) provides Cu-zeolitecrystals, followed by hybridization to covalently link nanoparticles ofmetal oxides to the surfaces of Cu-zeolite crystals.

Type-A Hybrid Binary Catalyst Synthesis

Step 1: Zeolite/Metal Oxide Hybridization

There are two hybridization procedures employed, using metal oxideprecursors:

Procedure A—metal oxide precursors were dissolved in acidic aqueoussolution, and the resulting mixture was vigorously stirred to obtain aslurry containing zeolite particles. The metal oxide precursors werethen reacted with the zeolite by neutralizing at elevated temperature(typically with 65° C.), with dropwise addition of ammonium hydroxidesolution.

Procedure B—two separate aqueous solutions of reactive precursor wereprepared. The first solution contained the zirconium precursor (andpotentially other precursors in acid solution), along with the zeolitepowder. Upon adding the second solution to the slurry, the hybridizationreaction occurred instantaneously.

Procedure A: Co-Precipitation of Precursors from Acid Solution

The following zeolites were used: nano-ZSM-5 zeolite (ACS), beta-zeolite(Tosoh USA), as well as custom synthesized SAPO-34, and SSZ-13.

Metal oxide precursor reagents in the appropriate stoichiometricproportions were mixed in deionized (“DI”) water with urea (a chelatingagent) to facilitate nucleation of the precipitating metal oxide(s) atactive centers (e.g., Al, Si and P species) on the zeolite crystalsurfaces. Examples of precursor reagents include zirconyl chlorideoctahydrate, ammonium cerium nitrate, potassium permanganate, cobaltnitrate hexahydrate, barium nitrate, ortho phosphoric acid, ammoniummolybdate tetrahydrate, calcium nitrate tetrahydrate, chromium nitrate,nickel nitrate, potassium permanganate, titanium chloride, tungstenchloride. This reagent mixture was a clear solution at room temperature.The selected zeolite was added to the clear solution in the powder form,with vigorous stirring to obtain a thoroughly mixed slurry. Optionally,random copolymer poly(ethyleneglycol-ran-polypropyleneglycol) (i.e.,PEO-PPO) may be added to serve as a surfactant to obtain optimaluniformity of nanoparticles size and distribution. Heat was applied tothe slurry and 28% NH₄OH solution was added dropwise (1 drop/sec), when65° C. was attained. The endpoint was established when the sol-gel pointwas surpassed, which was marked by a dramatic increase in viscosity.Vigorous stirring and continuous heating enabled the high viscosity todecrease, and additional NH₄OH was added to ensure that all of theavailable precursors or reactive moieties were hybridized to the zeolitesurfaces. Where cobalt precursor was employed, the endpoint wasaccompanied by a very distinctive color change from bright pink to“cobalt blue”. The lack of color in the filtrate and bright cobalt bluecolor of the retrieved product was a clear indication that the Co²⁺precursor (and other reacting precursors) was almost completelyhydrolyzed to the zeolite surface.

The entire mixture was either briefly quenched in an ice-bath orfiltered while hot. Washing was conducted with generous quantities ofdeionized water. The solids were washed, air dried, oven dried atbetween 105° C.-120° C. (1 hr), and then calcined at 600° C. (1 hr).

Procedure B: Incipient Co-Reactive Precursor Precipitation Step 1:Hybridization of Metal Oxide Nanoparticles on Zeolite

Two separate aqueous solutions of reactive precursor were prepared. Afirst solution contained the zirconium and other precursors that onlyreact when neutralized with NH₄OH, along with the zeolite powder to forma slurry. The second solution contained a metal oxide precursor, such asortho phosphoric acid, sodium vanadate, titanium chloride, and/orammonium molybdate. When the second solution is added to the firstsolution, the metal oxide precursors in the second solution reactedinstantly with the zirconium precursor(s) in the first solution; at roomtemperature or cooled to (−15° C.) to regulate the kinetics of thehybridization reaction to form metal oxide nanoparticles on the zeolitesurface.

Step 2: Copper Exchange Procedure

Copper sulfate solution was prepared in DI water at variousconcentrations (0.1, 0.25, 0.5, or 1.0M) and used to treat protonatedzeolite in a proportion of 500 mL copper sulfate solution to 100 g ofzeolite. 0.1M copper sulfate solution was used with and withoutconcentrated sulfuric acid adjustment to pH 3. The mixture was heated at80° C. for either 1 hr or 3 hr, with constant stirring. Thecopper-exchanged product was filtered, washed with generous amounts ofDI water, air dried, oven dried at between 105° C.-120° C. (1 hr), thencalcined at 550° C. (1 hr).

Type-B Hybrid Binary Catalyst Step 1: Copper Exchange Procedure

1M copper sulfate solution was incubated with zeolite at 80° C. for 3hours with vigorous stirring, and processed as described previously forType-A hybrid binary catalysts.

Step 2: Hybridization of Zeolite and Metal Oxide

Cu-Zeolite powder from Step 1 and metal oxide precursors were reacted asdescribed in the copper exchange procedure for Type-A hybrid binarycatalysts to achieve hybridization. The obtained product was furthertreated as described above for Type-A hybrid binary catalysts.

Characterization of Hybrid Binary Catalyst Materials

The following characterization techniques were used to study the HBCssynthesized above.

(a) Inductively Coupled Plasma (ICP) Spectroscopy, which providesaccurate elemental compositions.

(b) X-Ray Diffraction, which provides information on the structuralproperties (e.g., crystallinity) that relates to both composition anddurability.

(c) BET Surface Area Analysis, which provides both available surfacearea for catalyst reaction and porosity information, which in turncorrelates to access of reactants to the activity sites.

(d) Synthetic Gas Bench (SGB) performance testing provides emissionscontrol testing information when the catalyst is applied to a (1″×3″)monolith substrate in the form of a washcoat. Conditions simulatingon-engine test conditions are employed in this test so that realisticconclusions related to diesel emissions control can be drawn from theresults.

(e) Electron energy loss spectroscopy (EELS), which complements ICP byconducting elemental analysis in situ, without having to digest thesample in concentrated acid.

(f) Scanning electron microscopy (SEM) and scanning transmissionelectron microscopy (STEM) provide in situ microstructural and elementalanalysis, depicting the catalyst in its actual functional state.

(g) Thermogravimetric analysis (TGA) and Fourier Transform Infrared(FTIR) spectroscopy permit analysis of urea thermolysis kinetics, andthe potential impact of Type-B Hybrid Binary Catalyst compositions.

Results

A summary of the copper loading results achieved with four differentzeolites and their zirconium/barium Type-A HBC derivatives, using 1MCuSO₄ at 80° C. for 3 hrs are shown in Table 2. These zeolites representthe very broad range of zeolite types (including pore sizes). The cation(e.g., copper) loading ratio (CLR) for each zeolite type is defined aswt % Cu²⁺ in Cu-Zeolite/wt % copper in HBC.

CLR for the four zeolites presented in Table 2A are ranked in the order:β-Zeolite≥SAPO-34>SSZ-13>ZSM-5, which is inversely related to the totalbarium-doped zirconia metal oxide loading for the given zeolite.

The relatively high CLR value for β-Zeolite provides evidence that thecation exchange capacity power of the barium-doped zirconia metal oxidephase at about 3% of the HBC content, does not facilitate additionalcopper loading beyond that of the zeolite phase to the extent that wasexpected based on the ion exchange capacity for the metal oxide only(see Table 2B). On the other end of the spectrum, a relatively low CLRvalue for ZSM-5 correspond to the highest metal oxide loading of about5.5% content of the HBC. This data, in combination with that in Table2B, suggest that the copper loading by the metal oxide phase of HBC isdependent on both the amount of metal oxide phase present, as well asthe composition of the metal oxide phase. Furthermore, the cationloading capacity can play an important role in platinum group metal(PGM) binding to obtain highly distributed, high activity catalyticcenters, which can translate into lower PGM loadings, reduced tendencyfor deactivation by sintering, and reduced overall cost.

The relatively large pore zeolites (such as β-zeolite and ZSM-5) aredesirable for HBC use in DOC applications, due to their ability to storerelatively large quantities of hydrocarbons.

FIGURE 2A Cation (Cu²⁺) Loading Ratio for Different Zeolites in Type-AHBC Based on Zr and Ba. Cation ZrO₂-based Mixed Zeolite Zeolite (Cu²⁺)Metal Oxide Item Catalyst Composition Pore Copper Loading (wt % ± 10) #ID Al Si P Size Loading Ratio Zr Ba 1 ZSM-5 2.2 37.3   5Å 2 CuZSM5 #12.4 34.8   5Å 0.2 3 CuZSM5 #2 2.6 38.3   5Å 0.2 0.13 4 CuHBC- 2.1 35.6  5Å 1.5 3.2 2.5 ZSM5-ZB 5 βZeolite 2.2 37.5 5.5-7Å 6 Cuβ 2.8 37.55.5-7Å 2.3 7 CuHBC- 2.4 35.5 5.5-7Å 2 1 2.8 2 β-ZB(A) 8 CuHBC- 2.5 36.15.5-7Å 1.9 2.7 1.7 β-ZB(AP) 9 SSZ-13 2.6 36.6 3.8Å 10 CuSSZ-13 2.7 40.63.8Å 1.2 0.41 11 CuHBC- 2.4 36.7 3.8Å 2.9 3.3 1.4 SSZ13--ZB 12 SAPO-3417.2 3 17.2 3.8Å 13 CuSAPO-34 20.2 4.2 18.2 3.8Å 1.8 0.72 14 CuHBC- 18.13.3 16.2 3.8Å 2.5 3.9 0.6 SAP034-ZBIn Table 2A, the cation loading ratio (CLR) is CuZeolite/Hybrid BinaryCatalyst.The CLR ranking is β-Zeolite>[SAPO-34]>Chabazite >ZSM-5

TABLE 2B Copper Loading for Metal Oxides Under Equivalent ConditionsUsed for HPC Preparation (Note that solubilization of cerium wasincomplete in ICP procedure) Composition (wt%) Item Metal Cu # Oxide ZrBa Co V Ca Ce P Loading 1 CuZ 57.8 0.3 2 CuZB 41.5 19 2.2 3 CuZBCo 51.60.2 11.6 1.6 5 CuZBCoP 17.9 26.7 1.7 8.9 8.2 5 CuZV 34.2 26.8 1.7 6CuZVCa 11.8 47.3 0.6 0.8 7 CuZCe 46.4 6.9 0.2 (+)

Additional data describing the physical properties of the catalystcompositions shown on line item 5-8 in Table 2A (for β-zeolite), arepresented in Table 2C.

TABLE 2C Effect of PEO/PPO on BET Surface Area and Porosity forβ-Zeolite Based HBC (See also FIGS. 6A and 6B) BET HK Item # SurfaceMedian HK Maximum from Area Pore Width Pore Volume Table 2A Catalyst ID(m²/g) (Å) (cm³/g) 5 β-Zeolite 618 6.47 0.2436 6 Cuβ 642 5.71 0.2496 7CuHBC-β-ZB(A) 595 6.62 0.2345 8 CuHBC-β-ZB(AP) 803 7.83 0.3274

The BET data presented in Table 2C depicts the very dramatic increase inboth surface area and porosity that can be achieved when PEO/PPO isemployed in the hybridization process (item 8, Table 2A). This unique,high surface area and high porosity catalyst structure is an importantfeature of the catalyst compositions of the present disclosure. Ascanning electron micrograph image of this unique structure is shown inFIG. 6B. Furthermore, enhanced surface area and mesoporosity translatesinto improved emissions control performance under the highest spacevelocity conditions (e.g., ≥100,000 hr⁻¹) that can be encountered in aheavy duty diesel aftertreatment system. Comparing item 8 with item 7,the 34% higher catalytic surface area and 18% increase in HK mediandiameter available for the CuHBC-β-ZB (AP), makes it possible to uselower catalyst washcoat loading; with a potentially lower contributionto system ΔP (i.e., the backpressure on the engine that impacts fuelconsumption).

Evidence of the intimate chemical bond between the metal oxide phase andthe zeolite phase created in the hybridization process (involving Al andSi incorporation in the resulting metal oxide composition), is presentedin Table 3, where ICP, XRD and BET surface area data are presented forSSZ-13 and SAPO-34 Type-A HBC samples.

TABLE 3 Physical Properties of HBC Based on SSZ-13 and SAPO-34. Cu BETMetal Metal Oxide Loading Cu XRD Surface Item Oxide Ionic (wt ± Loading% Area # Catalyst Composition Conductivity 10%) Increase Crystallinity(m²/g) CuSSZ-13 Based Hybrid Binary Catalyst 1 CuSSZ-13 n/a n/a 1.2 n/a80-90 760 2 CuHBC- Zr = 6.4 Anion 1.2 0 ″ 620 SSZ13-Z 3 CuHBC- Br = 1.4Cation 3 150 ″ 590 SSZ13-ZB Zr = 3.3 4 CuHBC- Zr = 3.9 Cation 1.4 17 ″513 SSZ13-ZV V = 8.1 CuSAPO-34 Based Hybrid Binary Catalyst 5 CuSAPO-34n/a n/a 1.8 n/a 80-90 648 6 CuHBC- Zr = 7.3 Anion 1.9 6 15 294 SAPO34-Z7 CuHBC- Ba = 0.6 Cation 2.5 39 14 N/A SAPO34-ZB Zr = 3.9 8 CuHBC- Zr =5.2 Cation 2.8 56  8 91 SAPO34-ZV V = 5.1 9 CuHBC- Ce = 2.6 Anion 4 122 6 195 SAPO34-ZC Zr = 3.1

In Table 3, the metal oxide component of the HBC compositions weredetermined by ICP. By way of reference, pure metal oxides have BETsurface areas of <100 m²/g.

There are four important conclusions that can be drawn from the data inTable 3, with reference made to Table 2B showing Cu²⁺ loading capacityof various metal oxides prepared under equivalent conditions as the HBCType-A in the absence of zeolite particles.

1. Item 2 contains SSZ-13 HBC Type-A containing ZrO₂ (a known anionicmetal oxide), which exhibits relatively low cationic (i.e., Cu²⁺)binding capacity.

2. Metal oxide hybridized with SSZ-13 listed in Items 3 and 4 havestrong cation ion exchange properties, similar to or greater than thatof zeolites, and are thus able to bind Cu²⁺.

3. The SSZ-13 based catalyst compositions shown as Items 3 and 4 contain150% and 17% more Cu²⁺ (respectively), when compared with the amount ofCu²⁺ loaded onto the zeolite component.

4. A zeolite for HBC that is particularly advantageous is one thatexhibits good durability, as measured by retention of crystallinity (viaXRD) and high surface area (via BET), such as SSZ-13, in contrast toSAPO-34 zeolite. Table 3 shows that SAPO-34 and potentially otherzeolites containing heteroatoms (such as phosphorous that potentiallyintroduce added strain into the zeolite lattice structure), are lesssuited for HBC application due to the dramatic loss of crystallinity andsurface area. It is evident from these data that the intimateinteraction between structural components of the SAPO-34 zeolite duringhybridization with a broad range of different metal oxide compositionseffectively destabilized the crystal structure, causing it to collapseand form an amorphous (glassy) relatively low porosity material. Item 9contains a very dramatic illustration of impact of the hybridizationphenomenon on the structural integrity of SAPO-34, In this case,ceria-doped ZrO₂ is a well-known anionic metal oxide with minimal cationbinding capacity (see Table 2B, Item 7), but when hybridized to SAPO-34Type-A this mixed metal oxide shows an extremely high Cu²⁺ bindingcapacity. The inference drawn from this very surprising result is thatthe effect of “incidental doping” of the Zr:Ce mixed metal oxide byelements from the deconstruction of the zeolite result in an undefined,high Cu²⁺ binding end product. This inference is supported in a lessdramatic way by the data on Item 6 for ZrO₂ metal oxide, which is also awell-known anionic material and would not be expected to bindsignificant amounts of Cu²⁺ ions (see, Table 2B, line 1).

Presented in Table 4 are the composition data for CuSSZ13 and variousHBC derivatives prepared under different process conditions, wherecopper exchange was conducted with various CuSO₄ concentrations (andincubated at 80° C. for 3 hrs). The compositions were determined by ICPanalysis. Items 1-4 in the table illustrates the effect of CuSO₄concentration on copper loading; which leads to the conclusion that 0.1M(or less) would be optimal for minimizing excessive copper loading forbest NOx reduction performance, as demonstrated by U.S. patentapplication Ser. No. 14/486,858. Likewise, the pH 3 conditions used foritem 8 suggest that copper loading under such conditions should producehigh performance NOx reduction SCR catalysts, with less undesirable CuOformation (and corresponding N₂O-make). Items 10-14 pertain to Type-AHBC compositions, while items 15-19 are Type-B HBC compositions. Themost important distinction between the Type-A and Type-B compositions isthat the latter show distinctly lower copper loading, which result inlower NOx reduction, as measured by the Standard Reaction (in theabsence of NO₂), not shown here.

TABLE 4 Composition of CuSSZ13 and Hybrid Binary Catalyst Prepared UnderVarious Conditions SSZ-13 ZrO₂-based Mixed Zeolite Metal Oxide Item (wt%) Copper (wt % ± 10) # Catalyst Al Si Loading Zr Ba Co V 1 CuSSZ13 2.840.2 0.6 (0.1 M) 2 CuSSZ13 2.8 39.2 0.6 (0.25 M) 3 CuSSZ13 2.7 39 0.8(0.5 M) 4.1 CuSSZ-13 [A] 2.3 34.7 1 4.2 CuSSZ13 A′ 2.7 40.6 1.2 5.1CuSSZ13 [B] 2.4 35.9 0.9 5.2 CuSSZ13 B′ 2.8 41.5 1 6.1 CuSSZ13 [C] 2.335.5 1 6.2 CuSSZ13 C′ 2.6 40.9 1.2 7.1 CuSSZ13 [D], 2.2 33.7 1.1 18 hr @80° C. 7.2 CuSSZ13 D′, 2.7 42 1.3 18 hr @ 80° C. 8 CuSSZ-13 [G], 2.3 350.8 pH = 3 9 SSZ-13 2.6 36.6 — (protonated) 10 SSZ13-ZV 2.4 33.9 3.9 8.5Hybrid 11 CuHBC- 2.5 33.4 1.4 3.9 8.1 SSZ13-ZV (Type-A) 12 CuHBC- 2.433.1 1.2 6.5 SSZ13-Z (Type-A) 13 SSZ13-ZB 2.4 34 3.3 5.3 Hybrid (Type-A)14 CuHBC- 2.4 36.7 2.9 3.3 1.4 SSZ13-ZB (Type-A) 15 (Type-B) 2.5 35.70.9 3.1 CuHBC- SSZ13-Z(A) 16 (Type-B) 2.3 35.4 0.8 5.5 CuHBC- SSZ13-Z(B)17 (Type-B) 2 28.8 0.9 15.2 CuHBC- SSZ13-Z(C) 18 (Type-B) 2.4 35.2 1.12.9 1.9 CuHBC- SSZ13-ZB 19 (Type-B) 2.3 33.4 0.4 2.6 8.4 CuHHBC-SSZ13-ZV

The effect of the selected Hybrid Binary Catalyst Synthesis Procedure oncopper loading is illustrated in Table 5, where ZSM-5 zeolite is used tocompare and contrast Type-A vs Type-B Hybrid Binary Catalyst (where themetal oxide form the SCO phase). The most significant inferences fromthis data are:

1. Type-A HBC binds significantly more Cu²⁺ under identical incubationconditions, compared with Type-B.

2. Beneficial effect of copper loading might be expected to be greaterfor Type-A HBC compared with Type-B.

3. Increased metal oxide content of the Type-B HBC had no influence onthe copper loading, relative to that of pure CuZSM-5. However, increaseddiffusion limitation with increased metal oxide coverage of the copperzeolite can result in lower catalytic activity for NOx reduction.

4. Higher copper loading of Hybrid Binary Catalyst materials should beadvantageous, provided that this does not facilitate formation of CuOand other species that catalyze N₂O formation and other aging effects.

TABLE 5 Effect of Hybrid Binary Catalyst Synthesis Procedure on CopperLoading ZSM-5 ZrO₂-based Mixed Item Catalyst Zeolite Copper Metal oxide# ID Al Si Loading Zr Ba Ce 1 CuZSM-5 2.4 34.8 0.2 2 CuHBC- 2.3 36.9 0.23.4 ZSM-5-Z(A) Type B 3 CuHBC- 2.2 37.7 1.1 3.3 ZSM-5-Z(A) Type A 4CuHBC- 2 31.9 0.2 11.3 ZSM-5-Z(2B) Type B 5 CuHBC- 1.8 29.4 0.2 16.7ZSM-5-Z(C) Type B 6 CuHBC- 1.8 29.2 17.5 ZSM-5-Z(C) 7 CuHBC- 1.6 23.40.2 25.3 ZSM-5-Z(D) Type B

ZSM-5 zeolite was used as the model for screening a range of elements(referred to in Table 1), which convey desirable properties to theHybrid Binary Catalysts of this invention. Table 6 presents the IPCresults for Type-A HBC preparations that illustrate the versatility andbreadth of the catalyst compositions possible from the presentdisclosure. Line items 3, 5, 7, 9, 11, 13, 16, 20 represent ICP data formetal oxide compositions that have not been copper loaded. The resultsdemonstrate that a wide range of mixed oxides and related stoichiometriccompositions may be readily engineered to meet the requisite emission,durability and cost targets.

TABLE 6 Elemental Composition of ZSM-5 Based HBC Containing VariousElements in the SCO Phase Elements ZSM-5 Copper ZrO₂-based Mixed MetalItem in the SCO Zeolite Loading Oxide Composition (wt % ± 10) # PhaseHBC Al Si (g) Zr Ba Ce Co Mn P W Mo Ni Ti  1 Nil 2.4 34.8 0.2  2 Nil 2.638.3 0.2  3 Zr 2.3 36.5 3.3  4 Zr 2.2 37.7 1.1 3.3  5 Zr, Mo 2.2 36.42.9 0.1  6 Zr, Mo 2.1 36.3 1.2 2.8 0.1  7 Zr, Mn 2.1 36.1 2.8 0.8  8 Zr,Mn 2 35.5 1.2 2.8 0.5  9 Zr Ba, P 2.1 30.5 3.2 0.4 1.2 10 Zr, Ba, P 235.7 1.4 3.3 0.4 1.1 11 Zr W 2.1 35.2 2.7 4.5 12 Zr, W 1.9 35.4 1 2.73.8 13 Zr, W, Mo 2.1 36 2.8 2.3 1 14 Zr, W, Mo 2.1 36 0.9 2.8 1.8 0.4 15Zr, Co 2 35.1 1.2 3.3 2.8 16 Zr, Ba 2.3 36.4 3.5 2.6 17 Zr, Ba 2.1 35.61.5 3.2 2.5 18 Zr, Ba, Co 2.2 34.6 1.5 2.1 1.1 0.8 19 Zr, Ba, Co 2.437.5 1.2 2.4 0.9 1.1 20 Zr, Ce 2.2 35.1 2.9 3.8 21 Zr, Ce 2.1 35.9 1.32.9 3.9 22 Zr, Ce, Co 2.2 36 1.3 2.2 1.9 1.1 23 Zr, Ni, Co 2.2 36.4 142.2 0.8 0.8 24 Zr, P 2.1 36.1 1.2 3 1 25 Zr, Ti 2.1 36.6 1.2 3.4 1.4

FIGS. 6A, 6B, 7, 8, and 9 illustrate the unique physical characteristicsof HBC on both standard (i.e., microporous) and mesoporous zeolites. Twoof the four different types of zeolites used in this study are depicted(i.e., β-zeolite and SSZ-13).

A combination of scanning transmission electron microscopy (STEM) andelemental analysis has demonstrated that nanoparticles of metal oxides(2-5 nm diameter) can be clearly seen both on the outer surfaces andwithin mesopores of the zeolite crystals formed by the Type-A HBCprocedure. Furthermore, copper was located in both the zeolite and metaloxide when copper exchange was carried out after hybridization of metaloxide to zeolite. However, this was not the case for Type-B HBChybridization, where copper was primarily associated with the zeolitephase. In addition, Si and Al from the zeolite were also detected in themetal oxide particles. This indicated that the hybridization processinvolves a direct reaction with surface species in the zeolite.Therefore, metal oxide nanoparticle formation starts with nucleation atthe zeolite surface (potentially with the aid of the chelating agent),rather than with metal oxides forming in the bulk solution.

Example 2. Selective Catalytic Reduction (SCR) Performance of HybridBinary Catalyst

The following procedure was used to prepare and test HBC washcoats forNO_(x) reduction in a SCRF (1″×3″) core sample format.

Washcoat Procedure:

21% Cu-Zeolite or HBC catalyst, 73% DI water, 2% lactic acid, 2%poly(ethylene glycol-ran-propylene glycol) ˜2,500 Mn, 2% poly(ethyleneoxide) ˜300,000 Mv. This washcoat composition was applied to a (1″×3″)HiSiC 300 cpsi (Dinex) DPF substrate. The coated substrate was dried inair, then at 105° C. (1 hr), and finally calcined at 450° C. (1 hr).Typical catalyst washcoat loading on the substrate by this procedure wasin the range of 80-94 g/L.

The obtained catalysts were evaluated for NO_(x) reduction by a dynamicreverse lightoff NO_(x) reduction test and/or a high space velocityequilibrium reverse lightoff NO_(x) reduction test

Dynamic Reverse Lightoff NO_(x) Reduction Testing:

Each core sample was preconditioned at 500° C. in the gas mixture untilequilibrium was reached. Then a reverse lightoff test was performed; byallowing the temperature to slowly decrease and monitoring the SCRperformance as a function of temperature. The space velocity was 60,000hr⁻¹, and the following gas mixture was employed: 600 ppm NO; 600 ppmNH₃; 75 ppm ethylene; 300 ppm CO; 10% O₂; 5.6% CO₂; 6% water; and thebalance N₂.

High Space Velocity Equilibrium Reverse Lightoff NO_(x) ReductionTesting:

Each core was equilibrated at 450° C. for 30 minutes prior to conductingthe test, which is based upon realistic conditions encountered in aheavy duty diesel truck aftertreatment system. A series of equilibratedtemperature increments were used, starting from as high as 600° C. Thefeed gas contained 500 ppm NO_(x); and 600 ppm NH₃; with NO₂/NO_(x)=0,0.5 and 0.75. Ammonia oxidation was measured with 500 ppm NH₃ only, inorder to determine N₂O-make and N₂ selectivity. Also included in thefeed stream were 8.7% oxygen and 7.8% water. A total flow of 5,000NL/min (normal liters per minute) was established through the core, at aspace velocity of 100,000 hr⁻¹. These conditions were used as a stresstest to determine catalytic activity under realistic conditions, andalso to ascertain the adequacy of the catalyst loading on the substrate.

Results are shown in Table 7, and compare three ZrO₂-based HBC catalystSCRF core samples with a commercial reference (used to calibrate thesynthetic gas test bench equipment). Comparing the NO_(x) reduction atlow temperatures (i.e., ≤250° C.), it is clear that low temperatureperformance can be dramatically improved with the HBC. Hence, cold startand close coupled SCR application of such HBC compositions (with no DOCupstream) should afford superior performance than current aftertreatmentsystems. This is illustrated by CuHBC—SSZ13-ZB, where the metal oxidedramatically increases the NO_(x) reduction at 250° C. relative to thecommercial reference SCR catalyst. However, at higher temperatures thereis no further increase in the NO_(x) reduction. In addition, thiscatalyst was shown to produce 10 ppm NO₂ at 500° C. And when tested withNH₃ this catalyst exhibited NH₃ oxidation that resulted in ≥90% N₂selectivity, which means that this catalyst functions as a veryeffective AMOX; conducting NO_(x) reduction while preventing NH₃ slip.

It is reasonable to conclude that the hybridization conditions used(with no PEO/PPO employed in the procedure), resulted in considerableblockage of zeolite active sites for the CuHBC—SSZ13 catalystpreparation; resulting in diffusion limitation of reactants getting tothe active sites. This diffusion limitation can be overcome in one ofthree ways:

1. Reduce the metal oxide loading, while increasing the oxidative powerof the SCO phase.

2. Maintain the same metal oxide loading while improving the uniformityof the distribution for nanoparticles (in the 2-5 nm diameter range), byinclusion of a surfactant like PEO/PPO in the hybridization step.

3. Blend the given HBC with an unmodified Cu-zeolite to provideadditional NO_(x) reduction active sites that are unimpeded by thepresence of metal oxide nanoparticles, while the SCO phase is supportedon adjacent copper zeolite particles in the same washcoat.

The option described in (3) above is illustrated in Table 7 by the 50%CuSAPO34/50% CuHBC—SSZ13-ZB catalyst, where there was a marked increasein both low and high temperature NO_(x) reduction by blending. This is avery advantageous feature of the disclosure, where relativelyinexpensive zeolites may be employed for the HBC component in the blend,while the major component can be selected for its NO_(x) reduction anddurability properties

TABLE 7 Dynamic Reverse Lightoff Standard SCR Results for SelectedCuSSZ-13 Based HBC NOx Conversion Efficiency Wash- (%) at coat SpecificLoading Temperatures Catalyst ID (g/L) 150° C. 200° C. 250° C. 300° C.350° C. 400° C. 450° C. 500° C. Comments Commercial N/A 3 7 20 47 76 8282 Internal Reference Control for (2013) test procedure CuHBC- 90 13 4051 53 53 53 53 48 1. NO₂-make = SSZ13-ZB 10 ppm @ 500° C. 2. NH₃oxidation ≥ 90% N₂ selective 3. Improved low temp. deNOx 50:50 81 8 4562 62 66 72 73 68 Improved low Blend of temp. deNOx CuSAPO-34 and CuHBC-SSZ13-ZB CuHBC- 92 3 7 18 31 38 29 0 −28 NO₂-makeup SSZ13-ZV to 22 ppm @500° C.

In the case of CuHBC—SSZ13-ZV a unique combination of SRC and DOC (i.e.,SCO-like) properties were exhibited over different temperature ranges inTable 7; where NO_(x) reduction peaked at 38% (@ 350° C.), then declinedto zero (@ 450° C.) and declined to −28 (@ 500° C.). The lattercorresponds to the production of 20 ppm NO₂-make and only 10 ppmN₂O-make at 500° C. The DOC-like behavior of the CuHBC—SSZ13-ZV SCRFcore sample was verified in DOC testing (not shown here), and suggeststhat zirconium-vanadium containing HBC would be a good catalyst for PGMimpregnation to create a DOC, or even to form the basis of a 4-waycatalyst system.

The result of the high space velocity equilibrium reverse lightoff SCRperformance stress test for a CuHBC-β-ZBCoP is presented in Table 8. Thehighlighted (NO₂/NO_(x)=0.5) test conditions depict test results thatare directly equivalent to those obtained by J. H. Kwak et al., “TheEffect of Hydrothermal Aging on a Commercial Cu SCR Catalyst”,Directions in Engine-Efficiency and Emissions Research, MI, Oct. 5,2011, incorporated herein by reference in its entirety, for β-zeolite(fresh, where the space velocity was only 30,000 hr⁻¹. This result is ofimportant for the following reasons:

1. 50% lower catalyst washcoat loading on the substrate can be employedto meet the performance requirement of SCR under realistic operatingconditions; with only 84 g/L, compared with about 160 g/L or more forcommercial catalysts.

2. This is made possible due to the enhanced BET surface area andmesoporosity imparted to the catalyst as a result of the hybridizationprocess. In this process the surfactant (PEP/PPO) is utilized to achieveoptimal nanoparticle size (i.e., 2-5 nm diameter) and uniformity ofdistribution on the surface of the zeolite particles. The structuredescribed here is illustrated in FIG. 6B for a similar catalystcomposition, and the enhanced BET surface area and mesoporosity arelikewise illustrated in Table 2B line item 8.

TABLE 8 Equilibrium Reverse Lightoff NO_(x) Reduction forCuHBC-β-zeolite-ZBCoP (AP) Key Equilibrium Temperature Profile (° C.)Parameters Reaction 180° C. 220° C. 300° C. 400° C. 500° C. 600° C.NO₂/NO_(x) = 0 Standard SCR (%) 9.9 26 38.6 46.7 65.1 76.3 N₂O-make(ppm) 1 2.4 1.2 1.2 4.4 7.4 NO₂/NO_(x) = 0.5 Fast SCR (%) 45.5 69.4 88.190.1 89.4 N₂O-make (ppm) 55.4 74.1 46.7 31.1 30 NO₂/NO_(x) = 0.75 FastSCR (%) 95.3 95.8 91.6 N₂O-make (ppm) 94.6 70.3 58.3 NH₃ only Oxidationto form 0.1 0.7 N₂O (ppm)

Example 3. Diesel Oxidation Catalyst (DOC) Properties of Hybrid BinaryCatalysts Washcoat Procedure

Washcoats were applied to (1″×3″) HiSiC 300 cpsi (Dinex) DPF substrateas described in Example 3. Platinum group metal (PGM) catalyst wasapplied by an incipient wetness impregnation method, with nitrateprecursor compounds dissolved in 10 mL ID water. The solution containingprecursors was applied and a very low vacuum was used to ensure auniform distribution of PGM throughout the core. A dynamic reverselightoff protocol for DOC performance was used for testing, starting byfirst equilibrating at 600° C. The following feed gas mixture was usedat space velocity 60,000 hr⁻¹: 600 ppm NO; 75 ppm ethylene; 25 ppmpropylene; 7.5 ppm propane; 300 ppm CO; 10% O₂; 5.6% CO₂; 6% water; andthe balance N₂. The use of propane and propylene served as a morerealistic model for determining the ability of the catalyst toeffectively handle volatile organic compounds (VOC), which are a seriouschallenge in diesel engine emissions control.

Low PGM DOC compositions of Hybrid Binary Catalysts are presented inTable 9, where zirconium-vanadium and zirconium-barium metal oxides arehybridized to (3-zeolite. The following are the main conclusions fromthese data:

1. Hybrid Binary Catalysts that do not contain PGM are highly capable ofhydrocarbon oxidation. Particularly noteworthy is the oxidative abilityfor unsaturated, relatively long chain hydrocarbons (illustrated by thepropylene data). In the case of CuHBC-β-ZB (AP), line item 3 in Table 9,propylene lightoff temperature is lower and the percent conversion ishigher than that for carbon monoxide. Conventional wisdom believes thatexothermic lightoff of CO is required to facilitate the lightoff ofother species such as HC and NO. Here, the earlier lightoff andextremely high level of conversion of unsaturated hydrocarbons wasunexpected and surprising in the absence of PGM. This feature has beenengineered into the catalyst by employing zirconium as the primary metaloxide component, which when doped with other elements create oxygenvacancies (thus active oxidation sites) at the surfaces. Furthermore, byemploying barium as the dopant, a degree of NO_(x) storage behavior isalso afforded to the resulting mixed metal oxides. The result is arudimentary ability to lightoff NO at the moderately low temperature of350° C., and percent conversion efficiency

2. Impregnating such HBC with relatively low quantities of PGMdramatically improves lightoff and percent conversion for all speciestested (see item 4, Table 9). Indeed, 1-2 orders of magnitude lower PGMcontaining HBC catalysts have exhibited competitive DOC performance tothe commercial DOC reference used in this study.

3. Both zirconium-vanadium and zirconium-barium based HBC compositionshave been demonstrated to be very effective substrates for low PGMloading DOC; and are particularly suited for HC oxidation. This makesthese DOC catalysts ideal candidates for partial oxidation catalysts(POC), hence volatile organic compound (VOC) removal; and for 4-waycatalyst applications.

4. The oxidative power of zirconium-barium based HBC can besystematically modulated (both the magnitude and selectivity) by carefulselection of co-dopants. This is illustrated by comparing the DOCbehavior of the catalysts compositions in line item 6, 8 and 9 at thesame level of PGM loading, but different metal oxide phase composition.The most dramatic impact of starting with CuHBC-β-ZB (line 6) andincluding cobalt dopant to the zirconium-barium mixed oxide (line 8) isevident, and the further inclusion of phosphorous as yet another dopantto make a 4-component mixed metal oxide is illustrated in the CO,propane and NO_(x) lightoff and % conversion.

-   -   a. In the case of adding cobalt as an additional dopant to the        zirconium-barium mixed metal oxide, the lightoff temperature for        the saturated hydrocarbon (propane) was dramatically reduced.        But for NO there is no significant change.    -   b. Likewise, where phosphorus was added to the        zirconium-barium-cobalt mixed metal oxide, there was a dramatic        reduction in the CO lightoff temperature (by over 40° C.)        accompanied by a dramatic increase in NO lightoff (by 40° C.),        along with a large decreasing in NO conversion. This selectivity        is clearly related to changes in the metal oxide properties and        not PGM catalyst poisoning.

Thus, these data illustrate the ability of the catalysts of the presentdisclosure to systematically engineer the properties of the metal oxide(SCO) phase for hybrid binary catalysts in terms of both oxidative powerand resistance to poisons such as phosphorous and even sulfur.

TABLE 9 Low PGM Diesel Oxidation Catalyst (DOC) Performance of HybridBinary Catalyst Pd Rh Pt CO C₃H₆ C₂H₆ NO C₂H₈ CO C₃H₆ C₂H₆ NO C₂H₈ 1CuHBC- 0.1 nil 0.05 150 125 175 nil 250 83 95 69 nil 21 β-ZBV 2 CuHBC-0.1 0.05 nil 125 125 160 310 250 99 100 98 18 90 β-ZBV 3 CuHBC- nil nilnil 175 150 220 350 360 56 100 60 2 19 β-ZB (AP) 4 CuHBC- 0.01 0.0250.05 150 150 185 235 175 100 100 100 34 99 β-ZB (AP) 5 CuHBC- 0.05 nil0.05 170 <125 180 185 <125 75 86 49 9 ~40 β-ZB (AP) 6 CuHBC- 0.1 nil 0.1150 <125 180 185 460 92 97 80 19 ~10 β-ZB (AP) 7 CuHBC- 0.5 nil 0.5 125<125 170 175 420 86 96 76 29 ~25 β-ZB (AP) 8 CuHBC- 0.1 nil 0.1 165 125180 190 <150 97 100 86 20 ~40 β-ZBCo (AP) 9 CuHBC- 0.1 nil 0.1 <125 170190 230 ~150 97 100 86 8 ~30 β-ZBCoP (AP) 10 Commercial Zone <<150 170170 170 320 100 100 100 52 93 DOC Coated (>1 g/L Pt & Pd)

1. By increasing the PGM content to 0.5 g/L for both Pt and Pd, it waspossible to achieve legitimate DOC catalytic performance for NOconversion and dramatically lower propylene lightoff (by >45° C.);comparing line items 7 and 19.

2. Experimental evidence in item 2 and 4 suggest that even better DOCperformance can be achieved by incorporating Rh (along with Pt and Pd)in low PGM DOC compositions. This is potentially due to the enhancementof the already significant contribution of the following oxidativereactions due to the formation of palladium hydride (and rhodiumhydride) intermediates:

(i) Steam-Hydrocarbon Reforming Reaction

R—CH₃+H₂O═R—H+CO+2H₂  (Endothermic]

(ii) Water-Gas Reaction

CO+H₂O═CO₂+H₂  [Exothermic]

Example 4. Urea Hydrolysis Catalyst Properties of Hybrid BinaryCatalysts

Thermogravimetric analysis (TGA) was used to analyze HBC Type-B samples,using 50% urea solution, N₂ purge gas and 10° C./min thermal ramp fromroom temperature to 600° C. The study involved placing 14 (±1) mg ofcatalyst into an alumina TGA pan, followed by 40 (±1) mg of a 50% ureasolution. Thermal transitions from several replicate profiles wereobtained and analyzed to determine the temperature at which totaldecomposition of the urea solution was achieved (i.e., Td).

The results show that the HBC composition (CuHBC—ZSM5-Z (A) Type-B) wasmore effective in urea decomposing urea to produce ammonia by loweringTd by 38.3° C. (±0.3), relative to the conventional hydrolysis catalyst(TiO₂). This catalyst composition was 8% ZrO₂ hybridized onto CuZSM-5(after copper exchange and annealing of the zeolite). Therefore, thiscatalyst was also found to be an effective NO_(x) reduction catalyst.ZrO₂-based hydrolysis catalysts were described, for example, in U.S.patent application Ser. No. 14/486,858, herein incorporated by referencein its entirety.

TABLE 10 Urea Hydrolysis and NO_(x) Reduction Catalyst Performance ofZirconia-based HBC Peak NO_(x) Test Wt % ZrO₂ Copper ΔT vs ReductionConditions Hybridized Loading Td TiO₂ (NO₂-free) 50% Urea n/a n/a 393.1°C. n/a n/a 50% Urea/ n/a n/a 392.1° C. n/a n/a TiO₂ 50% Urea/ 8 0.2 wt %353.8° C. 38.3 28% CuHBC- (±0.3)° C. ZSM5- Z(A) 50% Urea/ 35 0.2 wt %379.1° C. 13.0 45% CuHBC- (±0.3)° C. ZSM5- Z(C) 50% Urea/ 50 0.2 wt %399.2° C. −7.1 — CuHBC- (±0.3)° C. ZSM5- Z(D)

Examples 5. 4-Way Catalyst Compositions

Examples of 4-way catalyst compositions in Table 11 are based uponspecific data presented in Examples 2-4.

TABLE 11 4-Way Catalyst Configurations Based on data from Example 2-4Urea DOC (POC) REDUCTANT Hydrolysis Zone Zone Zone SCR on DPF Zone AMOXZone 1. CuHBC- UREA CuHBC- 1. CuHBC- CuHBC- SSZ13-ZV/ SSZ13-SSZ13-ZB(AP) SSZ13-ZB(AP) ≥0.1 g/L [Pt—Rh—Pd] ZrO2(AP) 2. CuHBC- 2.CuHBC-β- SSZ13-ZBCo(AP) ZB(AP)/≥0.1 g/L 3. Blend: [Pt—Rh—Pd] CuSSZ-13/3. CuHBC-β- CuHBC-SSZ13- ZBCo(AP) ZB(AP) ≥0.1 g/L [Pt—Rh—Pd] 4. CuHBC-SSZ13- ZBCoP(AP) 1. CuHBC- Hydrogen Not Applicable 1. CuHBC- NotApplicable SSZ13-ZV/ SSZ13-ZB(AP) ≥0.1 g/L [Pt—Rh—Pd] 2. CuHBC- 2.CuHBC-β- SSZ13-ZBCo(AP) ZB(AP)/≥0.1 g/L ≥0.01 g/L [Pt—Rh—Pd] [Pt—Rh—Pd]3. CuHBC- 3. CuHBC-β- SSZ13-ZBCo(AP) ZBCo(AP) ≥0.01 g/L Pd ≥0.1 g/L[Pt—Rh—Pd] 4. CuHBC- SSZ13- ZBCoP(AP) ≥0.01 g/L Ni

Two exemplary 4-Way Catalyst scenarios are provided below:

1. Urea Reductant Scenario

The urea hydrolysis zone can be required when urea reductant upstream ofthe SCRF or SCR zone. This catalyst is selected to both enhance ureahydrolysis kinetics and can simultaneously contribute to NO_(x)reduction.

The DOC or POC (i.e., partial oxidation catalyst) zone facilitates NOlightoff for NO₂-make and provides effective HC oxidation for VOC(important soot components in the exhaust stream). As such, the POC iscoated onto a substrate with up to about 50% retention for particulates,so that the catalyst may oxidize the retained component. This provides amajor benefit by reducing the amount of soot entering the SCR on DPFzone of the filter. Note also that the HBC compositions are selected tocontribute to NO_(x) reduction, by virtue of the SCR/SOC nature of thebinary catalyst.

The SCR on DPF (i.e., SCRF) zone conducts the majority of the NO_(x)reduction; in addition to passively oxidizing soot to form ash. Thiszone further serves as a storage chamber for the ash, until an“ash-cleaning” event is required. The intervals between ash-cleaning aremarkedly prolonged by the inclusion of the POC zone, thus reducingmaintenance costs.

The AMOX zone provides a level of insurance against ammonia slip fromthe tailpipe, while carrying out NO_(x) reduction. Optionally, the useof relatively small amounts of PGM (e.g., in the 0.01 g/L range) mayalso be employed to provide an addition level of safety against ammoniaslip.

2. Hydrogen Reductant Scenario

It is evident from Table 11 that with hydrogen reductant the 4-waycatalyst is dramatically reduced in size, complexity and cost. Theincreased space can be used in a myriad of ways, such as to house anonboard H₂ generator.

While illustrative embodiments have been described above, it will beappreciated that various changes can be made therein without departingfrom the spirit and scope of the disclosure.

Illustrative, non-exclusive examples of descriptions of some methods andcompositions in accordance with the scope of the present disclosure arepresented in the following numbered paragraphs. The following paragraphsare not intended to be an exhaustive set of descriptions, and are notintended to define minimum or maximum scopes, or required elements orsteps, of the present disclosure. Rather, they are provided asillustrative examples of selected methods and compositions that arewithin the scope of the present disclosure, with other descriptions ofbroader or narrower scopes, or combinations thereof, not specificallylisted herein still being within the scope of the present disclosure.

A1. An engine aftertreatment catalyst composition, including:

a plurality of metal oxide nanoparticles hybridized to a metal zeolite,

wherein the metal oxide nanoparticle has a maximum dimension of from 0.1to 50 nm.

A2. The engine aftertreatment catalyst composition of Paragraph Al,wherein the metal oxide is hybridized to atoms located on a portion ofan exterior surface of the metal zeolite.

A3. The engine aftertreatment catalyst composition of Paragraphs A1 orA2, wherein the metal oxide nanoparticle has a maximum dimension of from0.1 to 30 nm.

A4. The engine aftertreatment catalyst composition of Paragraphs A1 orA2, wherein the metal oxide nanoparticle has a maximum dimension of from0.1 to 10 nm.

A5. The engine aftertreatment catalyst composition of Paragraphs A1 orA2, wherein the metal oxide nanoparticle has a maximum dimension of from0.1 to 5 nm.

A6. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A5, wherein the engine aftertreatment catalystcomposition has from 0.5 to 30 wt % of a plurality of metal oxidenanoparticles.

A7. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A6, wherein the metal oxide nanoparticle is selectedfrom cerium oxide, titanium oxide, zirconium oxide, aluminum oxide,silicon oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalumoxide, chromium oxide, molybdenum oxide, tungsten oxide, rutheniumoxide, rhodium oxide, iridium oxide, nickel oxide, barium oxide, yttriumoxide, scandium oxide, calcium oxide, barium oxide, manganese oxide,lanthanum oxide, strontium oxide, cobalt oxide, and any combinationthereof.

A8. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A6, wherein the metal oxide nanoparticle is selectedfrom the group consisting of zirconium oxide, vanadium oxide, ceriumoxide, manganese oxide, chromium oxide, cobalt oxide, titanium oxide,tungsten oxide, barium oxide, and any combination thereof.

A9. The engine aftertreatment catalyst composition of Paragraphs A1 toA8, wherein the metal oxide nanoparticle further comprises a cationicdopant.

A10. The engine aftertreatment catalyst composition of Paragraph A9,wherein the cationic dopant is an oxide comprising Mg²⁺, Cu²⁺Cu+, Ni²⁺,Ti⁴⁺, V⁴⁺, Nb⁴⁺, Ta⁵⁺, Cr³⁺, Zr⁴⁺, Mo³⁺, W⁶⁺, W³⁺, Mn²⁺, Fe³⁺, Zn²⁺,Ga³⁺, A13+, In³⁺, Ge⁴⁺, Si⁴⁺, Co²⁺, Ni²⁺, Ba²⁺, La³⁺, Ce⁴⁺, Nb⁵⁺, Sr²⁺,Pt²⁺, Pd²⁺, Rh²⁺, or any combination thereof.

A11. The engine aftertreatment catalyst composition of Paragraphs A9 orA10, wherein the cationic dopant is an oxide comprising Pt²⁺, Pd²⁺, andRh²⁺.

A12. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A11, wherein the metal oxide nanoparticle is selectedfrom CeO₂:ZrO₂, Y₂O₃:CeO₂, BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃,Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of O that counterbalances Zrand Ca, Zr_(0.5)Ba_(0.5)Mn₃O₄, Ba_(0.3)Zr_(0.7)O_(x) where x is anamount of O that counterbalances Ba and Zr, Zr_(0.5)Ba_(0.5)CrO₃,Zr_(0.5)Ba_(0.5)CoO_(x) where x is an amount of O that counterbalancesBa, Zr, and Co, TiO₂:CeO₂, ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇,Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount of O thatcounterbalances Zr, Ba, and V, TiO₂:ZrV₂O₇, each optionally comprising acationic dopant comprising an oxide of Ba²⁺, Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺,Cu²⁺, Ni²⁺, Fe³⁺, and any combination thereof.

A13. The engine aftertreatment catalyst composition of any oneParagraphs A1 to A11, wherein the metal oxide nanoparticle is selectedfrom ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇, TiO₂:ZrV₂O₇, Zr_(0.5)Ba_(0.5)CrO₃,Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of O that counterbalances Baand Zr, and CeO₂:ZrO₂.

A14. The engine after treatment catalyst composition of any one ofParagraphs A1 to A13, wherein the metal oxide nanoparticle furthercomprises phosphorus.

A15. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A14, wherein the engine aftertreatment catalystcomposition has from 70 wt % to 99.5 wt % of the metal zeolite.

A16. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A15, wherein the metal zeolite is selected fromaluminosilicate zeolites and silico-alumino-phosphate zeolites.

A17. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A16, wherein the metal zeolite further comprises acation selected from Pt²⁺, Pd²⁺, Rh²⁺, Cu²⁺, Ni²⁺, and Fe³⁺, and whereinthe metal zeolite optionally comprises an alkali metal ion selected fromNa⁺ and K⁺.

A18. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A17, wherein the metal zeolite is selected fromFe-doped aluminosilicate zeolites, Cu-doped aluminosilicate zeolites,Fe- and Cu-doped aluminosilicate zeolites, Fe-dopedsilico-alumino-phosphate zeolites, Cu-doped silico-alumino-phosphatezeolites, and Fe and Cu-doped silico-alumino-phosphate zeolites.

A19. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A17, wherein the metal zeolite is a Fe and/or Cu-dopedsilico-alumino-phosphate zeolite, and Fe- and/or Cu-dopedaluminosilicate zeolite, in combination.

A20. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A18, wherein the metal zeolite is selected fromFe-doped aluminosilicate chabazite, Cu-doped aluminosilicate chabazite,and Fe and Cu-doped aluminosilicate chabazite.

A21. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A18, wherein the metal zeolite is selected from ZSM-5,β-zeolite, SSZ-13 chabazite, and SAPO-34.

A22. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A21, wherein the catalyst composition has a thermalresistance of up to 600° C.

A23. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A22, wherein the catalyst composition has a BET surfacearea of at least 200 m²/g.

A24. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A23, wherein the catalyst composition is a dieseloxidation catalyst.

A25. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A23, wherein the catalyst composition is a dieselparticulate filter catalyst.

A26. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A23, wherein the catalyst composition is a selectivecatalytic reduction catalyst.

A27. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A23, wherein the catalyst composition is a ureahydrolysis catalyst.

A28. The engine aftertreatment catalyst composition of any one ofParagraphs A1 to A23, wherein the catalyst composition is an ammoniaoxidation catalyst.

A29. The engine aftertreatment catalyst composition of Paragraph A27,wherein the urea hydrolysis catalyst has a NO_(x) conversion efficiencyof at least 10%, when coated onto a surface of an impact static mixer,and wherein the urea hydrolysis catalyst is capable of decomposing ureato produce ammonia reductant in a diesel engine exhaust stream.

A30. The engine aftertreatment catalyst composition of Paragraph A27 orA29, wherein the urea hydrolysis catalyst binds and oxidizes SCRcatalyst poisons.

A31. The engine aftertreatment catalyst composition of Paragraph A30,wherein the SCR catalyst poisons comprise hydrocarbons, sulfur, or acombination thereof.

A32. The engine aftertreatment catalyst composition of any one ofParagraphs A27 and A29 to A31, wherein the urea hydrolysis catalyst is asacrificial catalyst.

A33. A method of making an engine aftertreatment catalyst composition,comprising:

providing an aqueous solution comprising a chelating agent and a metaloxide precursor selected from ZrOCl₂.8H₂O, NaVO₃, BaCl₂,(NH₄)₆Ce⁴⁺(NO₃)₄, KMnO₄, Co(NO₃)₂, Cr(NO₃)₃, CaCl₂, barium nitrate,ortho phosphoric acid, ammonium molybdate tetrahydrate, calcium nitratetetrahydrate, nickel nitrate, titanium chloride, and tungsten chloride;

mixing the aqueous solution comprising the chelating agent and the metaloxide precursor with a metal zeolite to provide a metal oxideprecursor-coated metal zeolite, and

calcining the metal oxide precursor-coated metal zeolite to provide theengine aftertreatment catalyst composition,

wherein the engine after treatment catalyst composition comprises aplurality of metal oxide nanoparticles bound to the metal zeolite.

A34. The method of Paragraph A33, wherein the metal zeolite is selectedfrom an aluminosilicate zeolite and silico-alumino-phosphate zeolite.

A35. The method of Paragraph A34, wherein the aluminosilicate zeolite isselected from SSZ-13 chabazite, ZSM-5, SAPO-34, and β-zeolite.

A36. The method of Paragraph A34, wherein the silico-alumino-phosphatezeolite is SAPO-34.

A37. A method of reducing NO_(x) in diesel engine exhaust in a selectivecatalytic reduction system, comprising:

exposing a NO_(x)-containing diesel engine exhaust to a catalystcomposition of any one of Paragraphs A1 to A32,

wherein the catalyst composition is disposed on or within a catalystsupport structure.

A38. The method of Paragraph A37, wherein the catalyst support structureis selected from a ceramic monolith and a metallic substrate.

A39. The method of Paragraph A37 or Paragraph A38, wherein the catalystcomposition is capable of decomposing urea deposits.

A40. The method of any one of Paragraphs A37 to A39, wherein thecatalyst composition increases NO_(x) reduction under cold startconditions.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An engine aftertreatmentcatalyst composition, comprising: a plurality of metal oxidenanoparticles hybridized to a metal zeolite, wherein the metal oxidenanoparticle has a maximum dimension of from 0.1 to 50 nm.
 2. The engineaftertreatment catalyst composition of claim 1, wherein the metal oxideis hybridized to atoms located on a portion of an exterior surface ofthe metal zeolite.
 3. The engine aftertreatment catalyst composition ofclaim 1, wherein the metal oxide nanoparticle has a maximum dimension offrom 0.1 to 30 nm.
 4. The engine aftertreatment catalyst composition ofclaim 1, wherein the metal oxide nanoparticle has a maximum dimension offrom 0.1 to 10 nm.
 5. The engine aftertreatment catalyst composition ofclaim 1, wherein the metal oxide nanoparticle has a maximum dimension offrom 0.1 to 5 nm.
 6. The engine aftertreatment catalyst composition ofclaim 1, wherein the engine aftertreatment catalyst composition has from0.5 to 30 wt % of a plurality of metal oxide nanoparticles.
 7. Theengine aftertreatment catalyst composition of claim 1, wherein the metaloxide nanoparticle is selected from cerium oxide, titanium oxide,zirconium oxide, aluminum oxide, silicon oxide, hafnium oxide, vanadiumoxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide,tungsten oxide, ruthenium oxide, rhodium oxide, iridium oxide, nickeloxide, barium oxide, yttrium oxide, scandium oxide, calcium oxide,barium oxide, manganese oxide, lanthanum oxide, strontium oxide, cobaltoxide, and any combination thereof.
 8. The engine aftertreatmentcatalyst composition of claim 1, wherein the metal oxide nanoparticle isselected from the group consisting of zirconium oxide, vanadium oxide,cerium oxide, manganese oxide, chromium oxide, cobalt oxide, titaniumoxide, tungsten oxide, barium oxide, and any combination thereof.
 9. Theengine aftertreatment catalyst composition of claim 1, wherein the metaloxide nanoparticle further comprises a cationic dopant.
 10. The engineaftertreatment catalyst composition of claim 7, wherein the cationicdopant is an oxide comprising Mg²⁺, Cu²⁺Cu+, Ni²⁺, Ti⁴⁺, V⁴⁺, Nb⁴⁺,Ta⁵⁺, Cr³⁺, Zr⁴⁺, Mo³⁺, W⁶⁺, W³⁺, Mn²⁺, Fe³⁺, Zn²⁺, Ga³⁺, Al³⁺, In³⁺,Ge⁴⁺, Si⁴⁺, Co²⁺, Ni²⁺, Ba²⁺, La³⁺, Ce⁴⁺, Nb⁵⁺, Sr²⁺, Pt²⁺, Pd²⁺, Rh²⁺,and any combination thereof.
 11. The engine aftertreatment catalystcomposition of claim 7, wherein the cationic dopant is an oxidecomprising Pt²⁺, Pd²⁺, and Rh²⁺.
 12. The engine aftertreatment catalystcomposition of claim 1, wherein the metal oxide nanoparticle is selectedfrom CeO₂:ZrO₂, Y₂O₃:CeO₂, BaZrO₃, Zr_(0.8)Sr_(0.2)CoO₃,Zr_(0.9)Ca_(0.1)O_(x) where x is an amount of O that counterbalances Zrand Ca, Zr_(0.5)Ba_(0.5)Mn₃O₄, Ba_(0.3)Zr_(0.7)O_(x) where x is anamount of O that counterbalances Ba and Zr, Zr_(0.5)Ba_(0.5)CrO₃,Zr_(0.5)Ba_(0.5)CoO_(x) where x is an amount of O that counterbalancesBa, Zr, and Co, TiO₂:CeO₂, ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇,Zr_(0.3)Ba_(0.1)V_(0.6)O_(x) where x is an amount of O thatcounterbalances Zr, Ba, and V, TiO₂:ZrV₂O₇, each optionally comprising acationic dopant comprising an oxide of Ba²⁺, Pt²⁺, Pd²⁺, Rh²⁺, Ru²⁺,Cu²⁺, Ni²⁺, Fe³⁺, and any combination thereof.
 13. The engineaftertreatment catalyst composition of claim 1, wherein the metal oxidenanoparticle is selected from ZrO₂, Y₂O₃:ZrO₂, ZrV₂O₇, TiO₂:ZrV₂O₇,Zr_(0.5)Ba_(0.5)CrO₃, Ba_(0.3)Zr_(0.7)O_(x) where x is an amount of Othat counterbalances Ba and Zr, and CeO₂:ZrO₂.
 14. The engine aftertreatment catalyst composition of claim 1, wherein the metal oxidenanoparticle further comprises phosphorus.
 15. The engine aftertreatmentcatalyst composition of claim 1, wherein the engine aftertreatmentcatalyst composition has from 70 wt % to 99.5 wt % of the metal zeolite.16. The engine aftertreatment catalyst composition of claim 1, whereinthe metal zeolite is selected from aluminosilicate zeolites andsilico-alumino-phosphate zeolites.
 17. The engine aftertreatmentcatalyst composition of claim 16, wherein the metal zeolite furthercomprises a cation selected from Pt²⁺, Pd²⁺, Rh²⁺, Cu²⁺, Ni²⁺, and Fe³⁺,and wherein the metal zeolite optionally comprises an alkali metal ionselected from Na⁺ and K⁺.
 18. The engine aftertreatment catalystcomposition of claim 16, wherein the metal zeolite is selected fromFe-doped aluminosilicate zeolites, Cu-doped aluminosilicate zeolites,Fe- and Cu-doped aluminosilicate zeolites, Fe-dopedsilico-alumino-phosphate zeolites, Cu-doped silico-alumino-phosphatezeolites, and Fe and Cu-doped silico-alumino-phosphate zeolites.
 19. Theengine aftertreatment catalyst composition of claim 16, wherein themetal zeolite is a Fe and/or Cu-doped silico-alumino-phosphate zeolite,and Fe- and/or Cu-doped aluminosilicate zeolite, in combination.
 20. Theengine aftertreatment catalyst composition of claim 16, wherein themetal zeolite is selected from Fe-doped aluminosilicate chabazite,Cu-doped aluminosilicate chabazite, and Fe and Cu-doped aluminosilicatechabazite.
 21. The engine aftertreatment catalyst composition of claim2, wherein the metal zeolite is selected from ZSM-5, 3-zeolite, SSZ-13chabazite, and SAPO-34.
 22. The engine aftertreatment catalystcomposition of claim 1, wherein the catalyst composition has a thermalresistance of up to 600° C.
 23. The engine aftertreatment catalystcomposition of claim 1, wherein the catalyst composition has a BETsurface area of at least 200 m²/g.
 24. The engine aftertreatmentcatalyst composition of claim 1, wherein the catalyst composition is adiesel oxidation catalyst.
 25. The engine aftertreatment catalystcomposition of claim 1, wherein the catalyst composition is a dieselparticulate filter catalyst.
 26. The engine aftertreatment catalystcomposition of claim 1, wherein the catalyst composition is a selectivecatalytic reduction catalyst.
 27. The engine aftertreatment catalystcomposition of claim 1, wherein the catalyst composition is a ureahydrolysis catalyst.
 28. The engine aftertreatment catalyst compositionof claim 1, wherein the catalyst composition is an ammonia oxidationcatalyst.
 29. The engine aftertreatment catalyst composition of claim27, wherein the urea hydrolysis catalyst has a NO_(x) conversionefficiency of at least 10%, when coated onto a surface of an impactstatic mixer, and wherein the urea hydrolysis catalyst is capable ofdecomposing urea to produce ammonia reductant in a diesel engine exhauststream.
 30. The engine aftertreatment catalyst composition of claim 27,wherein the urea hydrolysis catalyst binds and oxidizes SCR catalystpoisons.
 31. The engine aftertreatment catalyst composition of claim 30,wherein the SCR catalyst poisons comprise hydrocarbons, sulfur, or acombination thereof.
 32. The engine aftertreatment catalyst compositionof claim 27, wherein the urea hydrolysis catalyst is a sacrificialcatalyst.
 33. A method of making an engine aftertreatment catalystcomposition, comprising: providing an aqueous solution comprising achelating agent and a metal oxide precursor selected from ZrOCl₂.8H₂O,NaVO₃, BaCl₂, (NH₄)₆Ce⁴⁺(NO₃)₄, KMnO₄, Co(NO₃)₂, Cr(NO₃)₃, CaCl₂, bariumnitrate, ortho phosphoric acid, ammonium molybdate tetrahydrate, calciumnitrate tetrahydrate, nickel nitrate, titanium chloride, and tungstenchloride; mixing the aqueous solution comprising the chelating agent andthe metal oxide precursor with a metal zeolite to provide a metal oxideprecursor-coated metal zeolite, and calcining the metal oxideprecursor-coated metal zeolite to provide the engine aftertreatmentcatalyst composition, wherein the engine after treatment catalystcomposition comprises a plurality of metal oxide nanoparticles bound tothe metal zeolite.
 34. The method of claim 33, wherein the metal zeoliteis selected from an aluminosilicate zeolite and silico-alumino-phosphatezeolite.
 35. The method of claim 34, wherein the aluminosilicate zeoliteis selected from SSZ-13 chabazite, ZSM-5, SAPO-34, and β-zeolite. 36.The method of claim 34, wherein the silico-alumino-phosphate zeolite isSAPO-34.
 37. A method of reducing NO_(x) in diesel engine exhaust in aselective catalytic reduction system, comprising: exposing aNO_(x)-containing diesel engine exhaust to a catalyst composition ofclaim 1, wherein the catalyst composition is disposed on or within acatalyst support structure.
 38. The method of claim 37, wherein thecatalyst support structure is selected from a ceramic monolith and ametallic substrate.
 39. The method of claim 37, wherein the catalystcomposition is capable of decomposing urea deposits.
 40. The method ofclaim 37, wherein the catalyst composition increases NO_(x) reductionunder cold start conditions.